> Abraham being super willing to murder his son to make God happy.
Sacrificing your own children is a human behaviour so common through history and with different cultures, that it's basically a biological instinct. Even today parents send their sons to die in industrialized war to prove their faith for the government, as well as sacrifice their children in ways that are less explicit than that - always to prove their faith and loyalty to the entity they worship religiously, whether that's a man worshipped as a god, or a disembodied concept that they worship, such as "the state".
The story of Abraham is a way to break that spell. The primitive human instinct is to worship by giving gifts, and then naturally giving the greatest gift you can give to prove your faith, which is your child. I interpret the story of Abraham as a clever way to break one of the most evil and persistent traditions of humanity, which is child sacrifice. And the story is much more efficient than simply saying "You shouldn't sacrifice your own children".
Put yourself in his shoes (there have probably been thousands of Abrahams through time). If he says "I'm not going to sacrifice my child", the tribespeople will say that his God is weak because Abraham dares to give less of a sacrifice than the best, or that Abraham puts his own desires in front of what's good for the tribe (pleasing God or any god). If God told him to sacrifice his son and God later changed his mind, that's another thing.
The story puts an effective limit on the level of worship. Sacrifice animals sure, but don't sacrifice your own children.
Human sacrifice and ritual cannibalistic wars of genocide is the natural condition of humans as a species. That is the simple answer to why humans existed for hundreds of thousands of years without making any progress before something strange happened and we became enlightened.
Seeing as the Bible is a collection of stories that where told for thousands of years before being written down, I would think that there are entire generations and cultures who have live by those stories and commands for longer than the Bible has existed in any form. Pre-civilization tribes that we know nothing about. The Bible is our deepest probe into deep time, and absolutely fascinating.