Whatever is done at any given time is what has happened.
The perception of right or wrong is , as said in the OP, based on what seems to have been the result of previous situations or society trying to protect itself.
All actions have a reaction, what may seem 'good' will also have a 'bad' side
A 'bad' outcome may prove to have been a valuable lesson or may even turn out to be more advantageous.
If we were accepting of everything there would be no need for labels
As Neale Donald Walsch illuminated, humans have changed their list of "rights and wrongs" over time, over cultures and in different places.
We would never put people into battle as gladiators and cheer them to their death in this day and age would we? Why? Is it because because it is wrong? If it is wrong now, why was it not considered wrong back then?
It is apparently wrong to murder a person...... Yet, millions of people would go to war and kill not just one, but many other people to protect a multitude of things.
Right and Wrong are based on our feelings, and experience which change constantly.
"nobody does anything inappropriate, given their model of the world" - CWG
I don't completely understand your se nod part of the question, but I agree that good and evil do not exist. This includes. To only objective morality, but also subjective morality as well. Neither is there a uniform moral code for all, but there is also no way for a person to conceive of moral intuitions either. What we perceive as feelings of good and evil are actually anger, sadness, embarrassment, etc at we have mislabeled with moral terminiogy through ages of cultural construction.
But you would shoot it up if it would accomplish a goal. Eradicate ``enemies`` set by your higher authority that you are obligated to report back to to fulfill a mission or whatever. Good? Evil?
Bring wars into this. Pillaging others to gather for your country. Good? Evil?
Bring almost anything into this.
P.S reply in a comment back interested to hear back
Just wanted to add. Could have been brainwashed by morality and thought you were doing good BY your higher authority that it is OK to shoot up the room of people. Its all morality. No right or wrong. Manipulated.
You must not do something that would result in a consequence that you don't want. Would you shoot up a room full of people? No, because its wrong. Why is it wrong? For many reasons: the experience would probably not be very pleasing to say the least, and everybody would hate you and would try to make you as miserable as possible. Isnt it easier to just say its wrong? And yet, someone may hate a person, perhaps because that person has neglected the first person or abused them, and they may think it's right to kill that person. So right and wrong exist, because it's easier to use those terms to explain a choice than to explain every single thought that goes through your head when you make a decision.