These questions make me think of Plato's cave metaphor. Just because the people can only see shadows needn't keep them from developing complex theories about how to deal with shadows. The shadows are their best proxy for what's really going on, so the shadows are what we examine.

What's really going on? Our selfish genes are sorting out game-theoretical solutions to a tragedy of the commons, Hobbes's war of all against all. Kant captures the game theory view when he says, in effect, that doing what you would have others do is "right." Doing what you would have others do results in cooperation (coordination, in game-theory-ese), the key to plus-sum outcomes for groups of humans. The Golden Rule, however one comes to believe its worth, is the Great Coordinator. The rest, as the wise man once said, is commentary.

We are blessed with the ability to reify, to give names to strategies, to abstract "principles" from them. But every prescriptive moral statement is in effect a weaponized description of a strategy that has "worked" - whatever that means - in the past. One never says "Thou shalt not lie. YMMV." But that's how the world really is.

Either you roll the bowling ball directly at the pins, or you roll it at the spots on the lane that lead to success. The pros do the latter, because it works. Morality paints the spots on the bowling alley of life.