As it was in the days of Noah, so it will be at the coming of the Son of Man. For in the days before the flood, people were eating and drinking, marrying and giving in marriage, up to the day Noah entered the ark; and they knew nothing about what would happen until the flood came and took them all away. That is how it will be at the coming of the Son of Man.
Matthew 24:37-39 NIV
The Nephilim were on the earth in those days—and also afterward—when the sons of God went to the daughters of humans and had children by them. They were the heroes of old, men of renown.
But Noah found favor in the eyes of the Lord.
Genesis 6:4, 8 NIV
So are we acknowledging "them" now? Has the AF been studying them secretly for decades? Most likely.
As it was in the days of Noah, so it will be at the coming of the Son of Man. For in the days before the flood, people were eating and drinking, marrying and giving in marriage, up to the day Noah entered the ark; and they knew nothing about what would happen until the flood came and took them all away. That is how it will be at the coming of the Son of Man. Matthew 24:37-39 NIV
https://bible.com/bible/111/mat.24.37-39.NIV
The Nephilim were on the earth in those days—and also afterward—when the sons of God went to the daughters of humans and had children by them. They were the heroes of old, men of renown.
But Noah found favor in the eyes of the Lord. Genesis 6:4, 8 NIV
https://bible.com/bible/111/gen.6.4-8.NIV
Yes I've heard variations on that theme for years. "Us" from the future, "us" having already back-engineered captured UFOs, and so on. Fascinating.
It's likely our tech. "Their" tech, not to be confused with [their] tech, isn't observable for the most part. I think most sightings are our tech.