I think there are various assumptions which need to be addressed.

For one thing, good and bad are not some cosmic conflict between righteousness and evil, but the basic biological binary of beneficial and detrimental. The 1/0 of sentience. It's that in order to function, a society needs some collective contract. Which often has tended to treat insiders and outsiders differently.

One device to instill this moral code is the father figure lawgiver of monotheism. Though the logical fallacy of monotheism is that a spiritual absolute would be that essence of sentience, from which life rises, not an ideal of wisdom and judgment, from which it fell. Which is a very incendiary assumption, to assume one's ideals, which are aspirational, are absolute, which is elemental. Thus all the ideologies seeking to replace monotheism and its political manifestion, monarchy, have tended to treat their ideals as above question.

The basic fact is that we need to see these moral codes as tools, not gods. To supplement our need to make informed decisions, not rules to replace this conscious function.