I am answering this question from an Islamic scholar from the Shia sect named Ja'far ibn Sadiq but with will try to only speak in plain English
All human beings are born with senses of good and wrong and perhaps it is more intact within the first few years of a child and more cultivated by age and growth of wisdom, more damaged by sins and more preserved by kind acts. I said that to explain the differences among people's wisdom, that they all come from the same source, but are altered by age and growth of wisdom and by our actions
My argument is :
If you look at a young age child, you would see them to be the most truth telling, the most kindest until they see and learn from others how to do wrong and then by choice, but without sufficient knowledge they start lying from time to time or bother other people. Initially they are kind, they are honest... I mean 95% the first time a child talks he/she doesn't do it to lie...
Yet it's not complete, once they're coming of age, then their wisdom innately fruits into more kind deeds. Do parents really have to teach their children what is justice? Do they take a Justice 101 class at the age of 8 and then at the age of 10 they take Justice 102 and then age of 14 they take the class of the Humility 101 and Thanfullness 102? No!
The mother or father just says: " Hey my beloved daughter, it's not nice that you didn't thank your uncle for the birthday present" and the son replies: Uhum; And the matter is settled!( he wouldn't say what?! What are you talking about?! I don't know what thankfulness is! Please teach me)
Or if he cheats against her sister her father wouldn't say he sweety you have to go back to class and take not-cheating class again, its the 10th time you failed! He would just say, don't cheat and she would just say: I am sorry dad, I won't do it anymore!
How is it not the other way around!? That people are not injected with a moral compass to lie? How is it that they are pre-injected to tell the truth?
Humans are initially injected with Justice, Honesty, kindness, Hope,Thankfulness, Chastity, Mercifulness, Humbleness, peacefulness, forgiving, sympathy, Affection, Loyalty, Obedience,Love, Truth, Sincerity, Safekeeping, Kindness to parents, Concealment, peaceful, Cleanliness, Wisdom, Dignity,Repentance, Seeking forgiveness, Happiness
I guess part of the reason its not so obvious is that people's opinion or at least their actions are not all the same which leads us into thinking that this could be a result of us not having a similar base.
- IMHO Its that they are all gifted to us by a higher power, that higher power being God, yet through our free-will based sins we somehow scratch and deteriorate the cleanliness of our soul, of our nature!
For example for a person called Jack: The first time in his life, when he steals something, he simply goes and steals a chocolate bar from Starbucks... and then he realize that its bad, but hes doesn't care...the 2nd time, he goes and steals, but this time the sin of stealing becomes far less obvious to him...third time he goes and steals 2 chocolate bars... 5 months later, He has become a new person a person who is stealing 15 boxes of chocolate per day...2 years he is a person who is hiring people for his mob...5 years later he becomes is even willing to kill people... and this person becomes a person who will even argue with his own version of himself of 5 years ago, BECAUSE he didn't do anything to undo the damage on his soul, on his heart! Obviously this is an exaggerated version... I am just trying to explain the whole process of humans changing. Yet at every second people have the ability and free-will to change and become a brand new good person.
- How can we all not have the same understanding!? I mean it would be impossible for us to live together if my moral standards are COMPLETELY different from you. The similarity itself leads to a single creator.
- If you don't believe in God and the judgement day then forget this part, but if you do then: God cannot give human beings a wisdom, or source of intellect which for each person it functions differently and that it won't have any sort of touchstone... if our wisdoms don't have any touchstone then on the judgement day we could go to God and say " Hey Goddi... you know, no one taught me what is justice... no one taught me that I had to show kindness to my parents, therefor you can't send me to hell!" God's answer: I gave you wisdom so that you would know what is right and wrong.
- No person would say that lack of respect is good or that justice is
bad, God ( or the higher power if you don't believe in God) who has
gifted us our wisdom has made all of us aware, yet for every two
people you find it almost impossible for them to have the same
extent of understanding on the righteousness or evilness of the
action... for me the goodness could be 100X for you it could be
10000X. My point is, we are all on the same trajectory (because of
the same source of creation, but with different levels of
understanding because of our deeds, education and endeavor)