I don't believe we're moral out of a vacuum, I just don't believe that good and evil necessarily come from a demiurge, but rather from the desire to create society. The appeal of society is obvious. It allowed early people to be safer, diversify resources, and create a broader sense of community with their neighbors. But to live in even the most basic societies, people needed to create order. These probably started off really simply, “don't take my stuff, don't eat my goats, don't, erm, kill me”, and later developed alongside our increasingly-complex societies by necessity because without complex morality to protect its citizens a complex society would collapse in on itself. Without the ability to have a basic level of trust in the people around you, society doesn't work.
I'm not saying that there isn't a god or gods, because I don't know (and I do believe that there are metaphysical/spiritual forces that could be interpreted as god/gods at work in our universe). Perhaps the ability to have empathy and a sense of morality comes from a "divine spark" of some sort, I don't know. But what I do know is that systems of morality have developed all across the world, throughout all of history. The ancient Babylonians, Chinese, Greeks, Romans, and, hey look at that,
every other society had and have systems of morality to coincide with keeping law and order, for the stability of society. And the vast majority of them did it without any promise of eternal reward or punishment.
Just because you can't conceive of being a moral person without the thought of being punished, doesn't mean that others can't. It's not a perfect theory, but Lawrence Kohlberg's Stages of Moral Development would place such thinking in the first level of moral development: staying moral out of fear of punishment and/or out of hope for reward. Which, if you're curious, is explained fairly well here:
https://www.simplypsychology.org/kohlberg.html
As for the question of what would make God angry... I don't know. I've wondered that many times, and the idea of it is one of the driving forces that pushed me away from Christianity. But that's an entirely different discussion.