amen they weren’t literal giants they were rhetorical giants , men of great renown
“There were giants in the earth in those days; and also after that, when the sons of God came in unto the daughters of men, and they bare children to them, the same became mighty men which were of old, men of renown.”
Genesis 6:4 KJV
the world might say Elvis was a giant in music , Muhammad Ali a giant of boxing
we say this rhetorically the giants in the at verse there are the men of great renown and accomplishment think of it how much could we accomplish if we lived hindreds even near a thousand years like they did ?
the giants in the earth are the mighty men of great renown
“the same became mighty men which were of old, men of renown.”
If there were “ giants “ they would be more like Goliath rather than the four hundred foot giants that the book of enoch describes.
there still are large humans Robert wadlow was as tall as Goliath taller than a stop sign
I think if we look at Enoch’s account it basically falls apart when you realize he’s explaining almost five hundred foot giants supposedly born of normal women who were bedded by angels
and the scriptire sort of tells us the giants are the men of great renown born after Seth’s line mixed with cains line leading to the division your pointing to regarding noahs three sons
remember they were there during this time and would be there after also “There were giants in the earth in those days; and also after that,”
so they would have been before the cursing of Noah’s son
he’s cursed in genesis nine but the nephilim are noted already in the earth in genesis 6
It would have to go all the way back to cains seperation and the replacing of abel who cain killed , with Seth this is where the division of men began.
the two lines of men
“And now art thou cursed from the earth, which hath opened her mouth to receive thy brother's blood from thy hand; when thou tillest the ground, it shall not henceforth yield unto thee her strength; a fugitive and a vagabond shalt thou be in the earth. And Cain went out from the presence of the LORD, and dwelt in the land of Nod, on the east of Eden. And Cain knew his wife; and she conceived, and bare Enoch: and he builded a city, and called the name of the city, after the name of his son, Enoch. And unto Enoch was born Irad: and Irad begat Mehujael: and Mehujael begat Methusael: and Methusael begat Lamech. And Lamech took unto him two wives: the name of the one was Adah, and the name of the other Zillah. And Adah bare Jabal: he was the father of such as dwell in tents, and of such as have cattle. And his brother's name was Jubal: he was the father of all such as handle the harp and organ. And Adam knew his wife again; and she bare a son, and called his name Seth: For God, said she, hath appointed me another seed instead of Abel, whom Cain slew. And to Seth, to him also there was born a son; and he called his name Enos: then began men to call upon the name of the LORD.”
Genesis 4:11-12, 16-21, 25-26
you have Seth’s line and cains line separated there by God which continues through scripture