I couldn't follow you last point but Christianity came into being exactly because the bronze age OT wasn't possible to live up to. That's the whole spiel of the NT, believing takes up the slack.
There's no question morality was always a factor, but I don't agree that killing a woman for having sex out of wedlock was ever a moral thing to do just because it was written in a book. Or raping a single gal and marrying her for 50 shekels to smooth things over with dad. There are a whole bunch of laws that are bizarre, I would argue at any age.
If you need to compare the worse modern day examples with the best biblical age examples it means you aren't being even handed.
Thats what Jesus was talking about. It is said that when Jesus came the law became obsolete. I say the law will never be obsolete. What became obsolete was what Jesus called the traditions of men, what has become the Talmud, detailed instructions about how to understand and apply the literal letter of the law.
Jesus taught the the words of the law were figurative and the subjects hidden as was the deliberate intention of Moses.
Thats why Jesus did not stone the woman for adultery. The law has nothing whatever to do with human sexuality.
Thats why Jesus said "Eat my flesh. Kosher law has nothing whatever to do with what people serve and eat for meals.
His God and our God is not a God obsessed with diet and fashion and peoples sexual preferences.