We are taught to care for others' feelings and emotions. We must exercise certain deeds hailed in holy texts.
Why do such things matter when we all will die one day?
Even animals care for their young ones (their feelings and emotions also). This is an already-installed quality in most living things. Haven't you seen mother birds hatching their eggs? Will they hatch if no care is given? ...Bees caring their larvae? Are they all necessary to maintain the equilibrium of nature?
What would happen if no care (for feelings and emotions) is given to the disabled and the aged?
Think about the development of your language and your favorite pieces of music. If no care was given would they develop as you use or enjoy them now?
After reading the following, please don't blame me.
If nobody cared for you, your parents would leave you as a waste within a few hours of your birth. And you wouldn't get any food even for the first few days. Your mother also wouldn't get any care from others. I don't need to explain further. Here I linked 3 persons only. You may make this chain longer. Considering others also you may make or think of a web.
I don't need to explain your character (if you survived) if your parents and grandparents didn't get love and care from anywhere. I leave it for your thought. You will understand how civilizations develop.
We must exercise certain deeds hailed in holy texts.
This is not necessary everywhere (or in all categories). Try to read other holy texts also.
Man is a social being. He can't grow or develop without others' help.
From your question I guess you are asking about man as a being neutral in character (Whose deeds cannot be considered as good or bad).
(Although most often it is relative,) There are people having good and bad characters. You can live in this world without doing anything good. But you should be ready to accept its consequences without any complaints. And before saying "Yes", you should know one thing -- Every thing you are tasting/enjoying now is because other people and animals are maintaining love and care for others' feelings and emotions and also because they are doing good. Otherwise you would be living as member of an uncivilized primitive tribe. [I think even those primitive men care for their progenies' some feelings and emotions.]
Humans have developed brain and many things they experience will make impressions in their mind for a long time. Normally, he feels attachment towards things, places, people etc and becomes stronger as time passes by. You begin to say "these are my things, my people" etc. And their wishes, feelings etc are more varied than other animals'. As you know humans can control their feelings as well. Also, they have some special feelings like pride, shyness etc. They wish to be loved and cared by others. Since they can think better they always try to do and enjoy everything in a better way. The best way to fulfill their wishes, feelings etc is to be good and do good to others. And then only their mind will be free from worries. They know that.
Please understand this:
You may live in the society without any good character; without doing anything good. You feel problem only when you begin to ask some questions to yourself. (This happens especially in one's old age.)
E.g. I have enjoyed my life with the help of others. Did I do anything good for them in return?
Who am I really? What is the aim of human life?
I am born with many abilities and interests. Did I have a past life? If so will I have a posthumous life?
Where will I go after death?
Will I become a mere nothingness after death?
I wish to enjoy this world again. Will I be born here or somewhere else?
If these types of questions don't worry you, and if you don't do anything bad to others, there is no problem to them (i.e., to others).
But the final authority to decide whether there is any problem to you, is none other than you.
Mind is everything. It controls your whole life. Upon it depends your happiness or misery, success or failure. "Mana eva Manushyanam Karanam Bandhamokshayoh" thus say the Upanishads. Again, 'Yena Manojitam Jagat Jitam Tena' is the great truth. As you think, so you become. Do you fully realise now the great importance of controlling, training and overcoming the mind? So long you have neglected the care of the mind. Attend to this vital subject from now. Mastery of mind means success in all fields of life. To achieve this mastery you must study the mind. You must understand its nature, habits, tricks and the effective methods of bringing it under restraint.
To read the full text see: http://sivanandaonline.org/public_html/?cmd=displaysection§ion_id=476
If you wish to know the differences between man and animals, please read this:
If you found the things I mentioned above logical, (You may ignore the religious texts mentioned here) you may take it as base and try to understand holy texts. And you will certainly understand whether they are useful or not.
To do good implies to be good. To know more about its ultimate importance, please read the following extract from a website:
Satsangatve Nissangatvam Nissangatve Nirmohatvam Nirmohatve
Nischalatattvam Nischalatattve Jeevanmuktih ... Bhaja Gonvidan, Bhaja Govindam
Meaning: Sat sangatve - through the company of the good, Nissangatvam - (there arises) non-attachment, Nissangatve - through non-attachment, Nirmohatvam - (there arises) freedom from delusion, Nirmohatve - through the freedom from delusion, Nischala - Immutable, Tattvam - Reality, Nischalatattve - through the Immutable Reality, Jeevanmuktih - (comes) the state of 'liberated-in-life'.
Substance: The company of the good weans one away from false attachments; from non-attachment comes freedom from delusion, when the delusion ends, the mind becomes unwavering and steady and from an unwavering and steady mind comes Jeevat Mukti (liberation even in this life).
It is indeed a biological imperative to survive and also to procreate, as SonOfThought mentioned, so our biology gives us meaning, but it is a complicated question.
Your question is a fundamental question of nihilism. Answers are going to be a bit subjective. But in that subjectivity we can find an objective response: you can find your own meaning in life. Our lives can provide us with a level of subjective satisfaction, and that allows us to find meaning, even if the universe itself provides none.
We should care because after we all die, after the heat-death of the Earth when the sun expands, the only thing left from our entire lives will be the other persons with whom we interacted.
Jesus said, "I tell you, use worldly wealth to gain friends for yourselves, so that when it is gone, you will be welcomed into eternal dwellings." (Luke 16:9)
Turn the question around. What do you gain by not caring? If the holy texts are done with, and you wish to go beyond animalistic instincts, then in your new freedom you must use your mind to decide how to be.
Being selfish, greedy, violent, and in prison, probably aren't great ways to start, so better work out where you do want to get to. It neither matters, nor not matters. Mattering or it's absence are just props. Choose your props wisely.
One can view this from the perspective of divine command theory. Michael W. Austin describes this view of moral obligation as follows:
...Divine Command Theory is the view that morality is somehow dependent upon God, and that moral obligation consists in obedience to God’s commands.
An obligation requires someone with enough power to require this obligation. Call this authority a "king". If the authority is over morals, then the king is also "divine". Using the metaphor, "divine king" as source of moral obligation also suggests that one cannot talk back to this authority. One cannot ask the authority to explain Himself.
However, it is still one's responsibility whether one will obey or not, but there may be a price for disobedience.
This may be enough to tentatively answer the OP's question:
Why do such things matter when we all will die one day?
If the divine king is a Roman emperor, the reason to obey is to avoid dying a cruel death.
However, most of us live in a democracy with laws that separate church (holy texts) from state laws. The laws we are obligated to obey do not directly involve "care for others' feelings and emotions". Furthermore, we can talk back in a democracy and vote the legislators out. So we need to consider the question further.
G. E. M. Anscombe describes this situation in Modern Moral Philosophy. Austin summarizes her argument as follows:
On a law conception of ethics, conformity with the virtues requires obeying the divine law. A divine law requires the existence of God, as the divine lawgiver. Anscombe claims that since we have given up on God’s existence, we should also give up the use of moral terms that are derived from a theistic worldview. Since we have given up belief in God, we should also give up the moral understanding that rests on such belief, and engage in moral philosophy without using such terms. For Anscombe, this meant that we should abandon talk of morality as law, and instead focus on morality as virtue.
Anscombe suggests that attempts to reason our way to moral obligations will not work. The alternative to a return to a divine command theory is a return to Aristotelian virtue ethics or to obtain "an adequate philosophy of psychology".
A psychology would allow one to approach the moral problem of evil therapeutically. A philosophy of psychology would attempt to understand what evil is rather than what God is. M. Scott Peck provides a working definition of evil in attempting to construct a psychology of evil: (page 43)
Evil, then, for the moment, is that force, residing either inside or outside of human beings, that seeks to kill life or liveliness. And goodness is its opposite. Goodness is that which promotes life and liveliness.
This psychology would likely lead back to a divine command theory. Instead of focusing on God this back door focuses on avoiding the devil by growing out of certain personality disorders such as narcissism.
With that addition, let's return to the OP's question about why it matters whether we "care for others' feelings and emotions" or not if we will die anyway?
The therapeutic answer now becomes to live a healthy life, not to avoid a punishment for disobeying moral obligation.
Anscombe, G. E. M. (1958). Modern moral philosophy. Philosophy, 33(124), 1-19.
Austin, M. W. Divine Command Theory. Retrieved on July 7, 2019, from the Internet Encyclopedia of Philosophy at https://www.iep.utm.edu/divine-c/
Peck, M. S. People of the Lie. Simon and Schuster. 1983.