The Bible is not ignorant of the fact that degenerate societies have existed in the past (hence, Sodom). But it's never been on the worldwide scale that it is now, though. And not with the enormous population of billions of people engaging in it as well. Every day a thousand babies are murdered in America alone. By comparison the Phoenician child sacrifices to Moloch are quaint. Sin today is at a global industrial scale unimaginable to the Ancients.
Because they're irrelevant? The Bible isn't trying to be the Book of All Knowledge of Everything on Earth. The Old Testament is specifically about the history of ancient Israel as a civilization, and the New Testament is about the arrival of Messiah and the spreading of the gospel.
The Bible barely mentions Europeans, Africans and other Middle Easterners for that matter, too. I think Europe is not even mentioned until the New Testament - thousands of years into the history of the Bible. But it's obvious the Israelites were aware of Europe and traded with them even in the Old Testament days. A civilization being omitted is not necessarily out of ignorance of their existence.
If God set things up in a way wherein every soul was more or less guaranteed into Heaven, then it would defeat the purpose of this whole experiment. Free will is crucial to everything. Too much meddling on God's part kills free will. Unfortunately a consequence of absolute free will leads to situations like humans wandering off to live as savages, ignorant of God.
This is an extremely autistic, literal misinterpretation of the events. The crime in Sodom was rape, homosexuality, and pederasty. The story is referenced constantly even all the way until the New Testament, and it is plain via the context of all the other references to it that the intended point of the story was about sexual degeneracy.
Also, just because Lot offered his daughter does not mean the Bible condones this. This is the problem with atheists. The Bible records an event, and then atheists say that the Bible condones that behavior. No. Nowhere is this even remotely hinted at. Often the Bible is merely just a historical record of certain events. So what happens is that otherwise good men commit sins, but that does not mean that those sins are suddenly condoned or accepted. Lot's daughters fucked their father, but incest is still a sin. Isaac was a polygamist, but polygamy is still a sin. King David was a murderer and an adulterer, but murder and adultery are still sins. Joseph's brothers sold him into slavery, the Israelites began worshiping pagan gods, Peter denied knowing Christ, etc., etc. I could go on, but I think you get the point.