The ancient “mythologies” of the Mayan, Incan, Aztec, Greeks, Romans, Egyptians, Sumerians, India, etc. tell of “star people” “gods” etc. that came down among men and procreated, taught metallurgy, war, sciences, etc. This same story is told very briefly in Gen. 6. It is more thoroughly told in the Book of Enoch. As for 35 ft. tall perhaps that is what the 10 spies meant in Exodus when they said, “We are as grasshoppers to them.” This intermingling of unlike kinds, men and angels, is what led to the Flood and also to the extermination of some of the Canaanites when Israel entered the land.
I think this scenario will happen again before Christ returns. Jesus indicated it in Matthew 24 “as in the days of Noah” and it could also be referenced in Daniel 2:43 “they shall mix their seed with men but shall not cleave (marry) to them.”
It is this tampering with what God created (DNA) that concerns people today with genetic modification.