There are the equivalent of stone age humans in remote areas. They're human, they have human intelligence - but they haven't done anything with it.
If you took a brand new Jeep, gassed up, keys in it - they wouldn't know what to do with it - but even if eventually they figured out how to get it to run, they couldn't sustain it. They don't have the technology to make a compressor to inflate a tire, or plug a flat - charge a depleted battery even if they could figure out what the battery was and what it does.
It would be of any use the moment the gas tank ran dry. They have no oil, refining capabilities - nothing.
Intelligence, and what one does with it are not to be automatically equated. I recall in 1969, the same year we put a man on the moon, there was a NatGeo article of an expedition into a remote area - where cannibalism was still being practiced - and they were the equivalent of stone age humans. Same year! Two sets of humans. So different.
So when folks say these things are not very bright - because they don't have the wheels, or maybe they don't use fire - well, there's some humans likely still on this planet with just about the same degree of advancement. And both groups are doing fine. What we consider necessities - aren't.
Even if one has winter quarters in an impression, a cave, or a dugout - to reside closer to the summer herds - it's much easier to construct temporary structures to meet whatever structural needs one may find comforting.
And it's easy to differentiate between a construction or nature. It's even relatively easy to differentiate between nature and "pointers," or "indicators," or trail markers, or warning constructs.
Something that's clearly been manipulated - isn't nature.