Here is a fascinating article about so called primitive art and worth reading in full as well as enjoying the built-in slide show.
The idea that early man painted in this fashion or style because he had not developed the facility to do so is easily refuted by a visit to the Cairo Museum.
The familiar stylised depictions of ancient Egypt were just that, stylised.
They were well capable of verimisilitude in their paintings and sculptures and very much the equal of anything produced by Renaissance artists.
The greatest painter in history once said that he had spent his whole life learning how to paint like a child.
Here is the maestro himself showing how to produce primitive art and, by the way, this is nowhere near as easy as it looks. Try it for yourself if you don’t believe me.