I don’t think that’s entirely right, I don’t think we were capable of that yet. Prehistoric art was definitely trying to represent reality outside of the artist, but relied heavily on exaggerating important features.
In the cave wall art, the animals all have large, rectangular masses for bodies, and twiggy limbs by comparison. I believe the meat of the animal was most important, so the middle mass was exaggerated. A woman’s butt was attractive because we used to be quadrupeds, so they exaggerated the booty (and we still do). Large breasts and a rounded stomach indicated a woman was fertile/pregnant, so the artist made em big.
Prehistoric artists were like modern cartoon artists, exaggerating the important parts that were universally recognizable and important, and downplayed the bits we didn’t want to eat or mate with. Feet and hands weren’t too important.
If prehistoric art were abstract, we wouldn’t be able to walk into one of those caves and immediately recognize the animals, and immediately feel emotionally bowled over by the experience.