They may serve the same purpose as ship silhouettes.....................
I used to wonder about the same thing but came to a different conclusion.
For me, it closely mimics the process used when I was being trained to hunt AFV, IFV and APC so many many moons ago.
The vehicles were always done in as much detail as functionally possible. The methods of attack were drawn in a much more minimalist style.
Imo, those cave paintings are hunting lessons for the young sons.
Quite possibly. They may be a guide to show the methods used.................
They may serve the same purpose as ship silhouettes.....................