I have two children. One is gifted with high ability in art, and one is gifted with interest in art, but no special ability. Interestingly, both have won art contests. The reason as I see it is that the one with no special ability has a gifted child's ability to concentrate, put in a lot of time, and use humor and interest in his work.
This topic is of interest to me, and your son's work is unusual for 6. I see some skills which DD also had at that age. Just keep providing him with material, ideas, and encouragement. You may find, as we have, that he wants to learn technique and that no one teaches it anymore. Art classes and camps tend to be experiential with a focus on "cool materials" these days. YouTube can help if this becomes a concern.
