Very cool! I think the drawing shows interest, creativity, and ability to plan! As far as artistic ability, I'd be guessing. He represents figures symbolically, which is developmentally appropriate for his age. His artistic ability won't be apparent in symbolic or imaginative drawing though. It will show in observational drawing. "Drawing on the Right Side of the Brain" is the gold standard textbook. The reading will likely be too complex or boring for him, but the drawing exercises are appropriate if you explain them to him. Please take a look at it, he has potential and may surprise you if you can give him the instruction to get over the developmental hump into observational drawing.
I don't buy into the art as exploration approach. I learned to draw by observation rather than exploration. I don't perceive myself as "talented", but as having bypassed an ineffective way to teach art. Observational drawing first, THEN explore working with various media.
I would recommend getting drawing pencils in 2B, 4B, 6B, 8B, a sharpener, 100 grit sandpaper, and 8x12 paper - lots of it and preferably unbound. Paper quantity is more important than quality, although it should not be cheap. Look for paper that is not see-through, not mottled, and with a smooth surface. Avoid use of erasers! When he's ready for an eraser, get a kneaded eraser.
Expose him to as much art and as many styles as possible! His exploration into media will likely be driven by his exposure.
Enjoy the journey!
