No. what he se emerging in chapters six and seven is an increasing disintegration of the linage of the sons of Seth. Noah is the only one left of that line and indeed of that entire generation whom the Lord regarded as righteous.you dont get it do you the principle that you have applied should apply right through thus if it was the desendants of Seath it was all none exxempted the bible does not say that.
The text mentions angels nowhere. You are arriving at this conclusion simply on the basis on assumption.It is is simple fallen angel human wives giants = wickedness