Because they have biases just like anyone else. They look a ancient humans as ignorant savages and living in caves scrounging for food and killing strangers on sight.
While there may have been some of that, humans of post glacial period were intelligent and creative, eventually developing agriculture and industry, producing more than they immediately needed, so the rest was for trade to obtain goods that were not available locally.
We find arrowheads here in NW Florida that are made of flint, but there’s no flint here for hundreds of miles. Seashell jewelry is found hundreds of miles from any ocean where there is flint......................
Well said, RB.