Are moral values arbitrary? Its a question of game theory. Are traditionally "good" values (don't kill / don't steal) conducive to better social cooperation? Are empathic values conducive to better social cooperation? Do societies with better social cooperation outcompete the societies that don't cooperate in the long run? I think the answer is empirically "yes", these are objectively "better" values in the context of game theory.
The more aggressive your game theoretic strategy, the more you trade future benefits for short-term benefits. Perhaps the Romans occupied a middle ground strategy, moderately aggressive, moderately cooperative (they collected taxes instead of completely genociding their opponents). The Romans lasted, about 1100 years with this balanced strategy. Christianity posited a strategy that was even less aggressive, that traded the short-term benefit for obtaining the long-term benefit. Christianity has persisted for 2000 years.
Humans all have the necessary values built into them by evolution, but they can be convinced to suppress or exaggerate different values. If you are raised with Roman parents that essentially tell you, "The Roman strategy is the most superior one, look at our success at conquest!" Then they might configure themselves to align their values with the Roman strategy. If someone is raised with Christian parents that tell them, "Trust me, even though we are persecuted now, we will win in the end, because Jesus is coming back. Our strategy will work in the long run, have faith.", then the child will configure their values to be more closely aligned with that Christian strategy.
Thoughts from an interlocutor:
"5%-10% of people are good and truly do care about doing the right thing
5%-10% of people are malicious and immoral
The other 80%-90% of people are selfish amoral conformists who do what other around them do. People act pretty well today compared to the strong majority of history, but that' not because people have better character. It's because we have better public norms. The core of most peoples' morality is rooted in self interest
Most people will conform to the required social norms (and not much (if anything) more) because that's what they realize they have to do to function/be accepted by in the society they're apart of. However, if and when following those morals and decent social norms become more than slightly costly they'll drop whatever those morals are pretty quickly
There can often (but not always) be exceptions to this regarding close family (and maybe a couple of close friends). However, even in those situations such extended morality often still does have its limits"