God reduced the population to 8?
I don’t get your point but it sounds interesting.
Right! But the harm was already done. People had started using sex for fun, and once that starts there is no easy stopping it. If you consider the Bible chronological, i.e. the story of Adam and Eve came first, you can get the point that A and E ruined us for all time, until Jesus came. Even now it is taking a long time for the message to sink in, even among believers.
But the most important words in the Bible were the first words: I know that my Redeemer lives. All the rest of the Bible came later, including Genesis.