I don't really know if this is true or not, but they say that the first shape that chldren make, when they stop random scribbling, and start drawing is the circle.
You do find lots of drawings by children. I love this particular phase, called the tadpole stage, when children make pictures that are symbolic rather than representational. Children all over the world make this style of drawing. This one was made by William Robinson at 4 1/2.