Only a few things I would have to say.
It was God’s mercy that he sent the flood to protect and preserve human DNA from totally being corrupted.
I did offer in my past comment that all flesh, not just humans flesh, DNA got corrupted , save only what DNA of all flesh that was still pure.
The bible tells us that “ the fallen ones “ came before and after the flood.
The bible only tells us that only the good angels were not allowed to marry, those were the ones who did not leave their first estate.
Though out the bible there are many instances that the good angels were mistaken for men, human form.
How can that be if they are only spirits ?
What about the 2 angels at the garden tomb of Jesus Christ at his resurrection that Mary and the other women saw who they thought were the gardeners or men ? Human form.
The bible is silent on many things we can not explain.
The only reason why the fallen angels were allowed to marry human women and mate was that they were in rebellion against God.
Sorry, I do not buy that theory that they were of the of Cain, if Cain’s seed was totally wiped out by the flood, who then , according to the bible that there were giants before the flood and after the flood and God only saved the seed, the DNA of Noah and his family.
So as in the day of Noah, so shall it be in the days of the return of the son of God.
The UFO phenomenon and the so called aliens from another planet or galaxy are not what Hollywood, or others would have you to believe, the aliens, the UFOs are thefallen ones.
You and I seem to largely agree on the matter - Thx for your reply. :)