I'm in no position here to push you in one direction or the other. Because it's sheer speculation. God has left it vague. And then, perhaps, so should we. The bottom line, however, is clear.
Humanity is poisoned and dragged even lower than it was before.
We thought there was light, hope again for humanity, with Enoch. But no - things went right back. And then, with Lamech, we hope that with the birth of Noah things would begin to improve. We are confronted with these strange, dark verses. And God brings down judgement - limiting the life of humanity to 120 years, max.