The last of the Nephilim, maybe. There are many newspaper accounts from the 19th century about the discovery of giant humanoid skeletons in North America - however, they seem to disappear after being turned over to the Smithsonian museum people.
The point is that what happened before could happen again. Demons could possibly once again copulate producing offspring...
Absolutely! Red-haired giants, some with six fingers, were reported many many times in the 1800’s and early 1900’s in the Western US with many of those reports in newspapers of the time. And to your point, someone from the Smithsonian would come down and get the evidence and then it was never heard from again. I know it sounds nutty, but there is some basis for this.
As for the US military or Government’s interest in keeping this secret, I can see it. If the mighty US government were to admit that there were giants and the military had killed some but we had covered it up for dozens or hundreds of years, that would erode even more trust, and thus would lessen their power over all of us. No positive outcome for government interests in confessing about this or anything else, really.
My favorite giant story:
https://www.ancient-origins.net/myths-legends-americas/lovelock-cave-tale-giants-or-giant-tale-fiction-003060
yes