There is a point in ethics where the question stops being about "morally right" and "morally wrong" and it turns into "morally obligatory" "morally permissible" and "morally impermissible." Its not that "right and wrong" or "good and bad" don't mean anything, it's more so that they don't encapsulate the entire story just on their own.
Morally obligatory means that the action is good and you, as a moral agent, are under an obligation to do that action. Remember that a moral agent is someone who has the ability to make decisions based off of moral reasoning and they can be held accountable for those actions. If someone is trapped under a car and you have the ability to assist them without causing any inconvenience or harm to yourself, many ethicists would agree that you are morally obligated to help that person.
Morally permissible means that an action is not outright wrong. Some people make the argument that abortion is morally permissible, that is, it is not necessarily a "morally good" action to have an abortion but it is also not "morally bad". A large amount of people say that abortion in the case of incest or rape, or when having the child would have serious medical ramifications for the child or mother, is morally permissible.
Morally impermissible is something that is not obligatory or permissible. Many people would make the argument that as a moral agent, if you went and murdered somebody with no provocation or any sort of rational reasoning behind it, that would be a morally impermissible act. They would argue that you, as a moral agent who is capable of reasoning about the ethical implications of actions, have done something that is not allowed by any rational thought about ethics. You took somebody's rights to their life away, you committed a horrible act and you understood the harm in doing so, so that act is obviously impermissible.
There are obvious cases where it would be easy to say "you committed a morally impermissible act and that was morally wrong of you" but there are other cases, like your example with buying alcohol, where the act wasn't outright morally right or wrong, it was just a morally permissible action.
As for animals, especially before contemporary thoughts on this subject, most people argued that animals are not rational moral agents. They argued that the animals don't understand what it means to be ethical, they can't reason within an ethical system, so their actions are not made as a moral agent. As such, we can't assign ethical values to their actions. An animal might kill to eat another animal, but most people would argue that the animal doesn't understand the concept of "murder" or "right vs. wrong" so its not that their actions are neutral, its that they aren't acting with moral agency, they aren't a rational agent. We are moral agents, we understand ethical reasoning and we understand, to a large extent at least, what is morally impermissible and what is morally permissible, therefore acting like an animal isn't an excuse to commit morally impermissible actions.
A strict Utilitarian view is that we are morally obligated in every situation to do the action that maximizes utility (happiness, well being, or however else it is specifically defined). Again, a strict view would be that if you are given two options and one of them is morally obligatory, it increases utility more than the other action, it would be morally impermissible to do that action. Not all Utilitarians believe in the strictest view and some might see your example of buying beer as a morally obligatory vs a morally permissible action.