I will point out that it would have been difficult for a caveman to go 300 meters above Spain at the time ....
Really though .. Is this much different than todays’ vandals (er, graffiti “artists”) climbing as high as they can to tag buildings, bridges, and walls as high up as people can see?
I will point out that no one knows that cavemen couldn’t do their art 300 meters up.
How many people have looked?
Given the vagaries of weather and the time factor maybe nothing is left up there too see.
It may have been so easy even a caveman could do it.