I recall reading about something like this.
I believe the wall paintings were made in such a way that the flickering of fire-light would give an impression of movement.
A good way to help story telling and oral history. Pretty clever for ancient humans. The days of lore.....
I also read that in many cases the paintings were placed in an area that had a good echo. It is thought (by archaeologists and researchers) that the ancient humans placed many of their paintings in area's of a good echo, probably thinking of some spiritual connection.
Everybody loves a good mountain echo....