I'd believe it. I've seen some old (not ancient) charcoal drawings in a limestone cave on Guadalcanal, Solomon Islands. The drawings were mainly of head hunting boats and war axes from the Western Province (from a different area the cave is in). The cave is hidden a couple of miles inland from the coast. The scenario would likely be that the war canoes turn up, the men stay to defend and the women and children run inland to the safety of the cave, then draw what they have seen on the cave walls.
My other scenario is a mother yelling "would you kids stop drawing on the cave walls!!!!". If it's like my house, that would be much more like it.