What is God's role in humanity's understanding of morality?

I was struggling with a response to this question and some thoughts came to mind that I’ll put down here. I’d’ve asked them in the thread but they aren’t really related to Satan so much.

Mostly I am asking these questions to understand what the religious folk feel.

@Nullo said that our moral standard comes from God (or, I’m presuming, some form of God or gods) and people then appropriate that standard for their own lives while at the same time rejecting its divine source.

My question(s), then:

Where does morality come from? Where does our understanding of it come from? How do we know (in a religious context, not a social one) what is moral and immoral?

Can people be moral (‘good’) without God? And if we are able to reject God and still maintain some moral sense, as @Nullo says, can we do likewise with Satan and still know or recognize ‘evil’? Following that, what use is there for God and Satan as ideas or presences in life? Does this suggest (I’m just reaching here) that God and Satan are only the anthropomorphic representations of humanity’s preexisting conceptions of what is good and what is bad?

I agree with those saying that most people’s understanding of morality still comes in some distilled or diluted form from a religion or doctrine.

But which came first: morality or man? If God (or some god) produces a moral standard, how does He (it) communicate that standard to humanity? We have the Commandments, but a moral standard obviously existed before that. What novelty or new morality does the presence of a divine being provide? Are we just attributing our own moral choices to a higher power, for no good reason?

Does the attribution of morality, or of ‘good’ and ‘evil,’ liberate humanity from culpability when it does something bad? (I.e., the ‘devil made me do it’ excuse, etc.)

I am not a religious person and so these things are all very confusing to me.