Perhaps I can be of assistance, with regard to your question about the Nephilim.
They were the offspring of fallen angels that abandoned "their homes" or angelic souls, and procreated with the daughters of men. They went on to be men of renoun because of their superiority, geneticly speaking. However they became violent in their ways and God saw fit to destroy them in the great flood of Noah. The Angels that went after strange flesh are now in the darkest dungeons, as stated in the book of Jude. Half angel, half man, the Nephilim, there you go. God never called Adam human. God called him Man. Did you know that the Chinese word for dragon is hu???
Hmmm...... dragon man, violent in his ways, slated for destruction HMMMM indeed