I find this question quite lovely.  Just read it in “Children’s Drawings as Diagnostic Aids” by Joseph H. Di Leo, MD, 1973 (Brunner/Mazel , Inc.).  I adore this book- a treasure I picked up at heaven-on-earth Powell’s City of Books, Portland Oregon in 2008.

Imagination frees the spirit from the bonds of reality.

The child, in his early attempts at representation, does not try to draw the object as it looks but the idea, the internal model, and produces a schematic reduction to essentials.