Because the Nephiliam had the status of supernatural spiritual beings--evidently with tangible bodies as well.
Humans did not. Humans were removed at the flood, according to Scripture--except for the 8 in Noah's boat.
Interestingly, the Chinese word for a very large boat--has the generic character for boat in it plus the character for person(s) and the character for 8.
Quix - Because the Nephiliam had the status of supernatural spiritual beings--evidently with tangible bodies as well.