This is apparently the first time God starts giving a damn about daughters. It’s also when he decides to wipe out almost all of mankind. It’s hard to think this is just a coincidence.
The opening of the chapter has a lot of oddities that need mentioning. The narrative seems to be making a distinction between “sons of God” and “men”. We are again seeing that not all people are accounted for as part of Gods creation. Daughters of men were beautiful and the sons of God married any of them that they chose. Apparently this bears mentioning because God doesn’t like this. It’s all a rather confusing jumble of non-sequitur. Next is some seemingly random line about “Nephilim” and how their sons were heroes. Who the hell are the Nephilim? (I’m assuming some kind of angel, but it’s not mentioned in the story so far)
Either way, we quickly get to the meat of the chapter: God is unhappy. Read in the light of when I just mentioned, God is apparently unhappy that the daughters of “man” have corrupted his “sons” and made them wicked. Again, it’s confusing about if he made all the men who exist, or just the line of Adam, but either way, he’s decided to wipe them ALL out.
God has decided that all men must die, and is throwing in all the animals for good measure. W. T. F?
Yet, of all the men on earth, one is OK. Noah finds favor is God’s eyes. He was righteous and blameless. We don’t know how or when he did differently, but God thinks that he should be saved and all other should die. The exception is Noah, his wife, his sons and their wives. Apparently this corrupt world was able to produce 3 women outside of Noah’s family worthy of rescue. How fortunate! Not an infant, not a girl, not even a puppy is worth saving of the whole earth.
Noah gets instructions about building an ark and bringing 2 of every kind of animal, male and female (presumably to breed more later).