I have to disagree a bit because if you look in detail at human evolution, I think you can find a pretty solid explanation of this. Of course you'll need to understand instinct, a very slippery subject.

You wrote: " But nature can’t tell us how to be moral because morality is about the freedom and mindful, heroic creativity of resisting nature’s palpable amorality." I'm not sure where you came up with that assumption, but you might want to glance at https://working-for-the-future.medium.com/how-to-solve-the-worlds-problems-b3f757f2aaa for a different point of view. It is about morality being related to survival strategy. Skip the first third if you want to get to that part faster. I'm still refining the whole thing.