I absolutely love the amount of detail that went into the boy and the tree. The hair system is especially well done imo.
I’ll echo the comment about a shoe falling off as it would add a little interest.
Actually I think the image itself has too much blank space. Maybe change the camera’s perspective a bit. Like down on the ground near the dog looking up at the kid, or up in the tree near the squirrel looking down on the kid. That might make a more dramatic composition, and give it some (perhaps exaggerated) perspective, as well as more interest.
Overall you’ve done a really good job though, kudos.