Sometimes a cigar is just a cigar.
Yes these are humans from a time when the Earth was much larger. The Earth was called by a different name by its inhabitants. Tiamat. It was natural and normal for the species of life on an 'Earth" many times larger than it is now. There is no mystery to this. There is no magic or demon seed that was planted.
Now when I tell you this very famous landmark, (Close Encounters of the Third Kind and many other movies and series through the years looking for an enigmatic location shoot.) is not some ancient mountain top but an even more ancient TREE STUMP. What does that concept do to your sensibilities concerning what you think you know of human history? Your Cosmic Guy is here to tell you that humanity is much older than any book claims.
One must consider the colossal amount of evidence that proves this Earth was a much larger place to live and thereby EVERYTHING was naturally larger. It is reported that humans from this era lived for several thousand years at a stretch and were on average 75 feet tall.
This is not the only picture like this, and keep in mind "these" humans were on average only 15-20 feet tall. They are not the 75 foot humans. That femur would be much larger.
Another example. Does this really look like a mountain top to you?