I believe they are nephilim, children of fallen angels and women.
Furthermore, those fallen angels also mated with animals, corrupting God’s creation. Which is the real reason of the flood of 40 days and 40 nights.
Either all of The Holy Bible is true or none of it is.
Keep in mind, the devil is prince of this world, if the government didn’t cover this up, then that would give credence to The Holy Bible.