Could be the work of one “artist”.
I see no details as to how they were protected from the environment for so many years. Were they in a cave?
BINGO!
Kind of interesting how, in the bottom photo, the lines are so sloppy and then at the bottom the black and white checkers are so neat and straight. Kind of thing that makes you go, ‘hmmm’. cackle cackle cackle
the newfound art "represents a new culture previously unknown,"
So, the tribes were there before Spain and Portugal were actually on “STOLEN LAND!”stolen from someone earlier. Been happening for the last 20 thousand years or earlier.
They know the paintings are genuine because they also found a Certificate of Authenticity.
I saw a BBC film where Steve Backshall and some guys rock-climbed to the top of that thing. It was one harrowing expedition, and it was obvious why caves on it might go undiscovered (and unexplored) for forever and a week.
https://www.bbc.co.uk/programmes/b073gr87/episodes/guide