Wow, the juxtaposition of innocent wonder and harsh reality is really striking. The boy, having found something he thinks is cute and fluffy, is smiling wide. But, we as the observer are left to wonder ourselves just what this little creature looks like. We can't see its face, so we cant judge for ourselves what its intentions or predispositions might be. Almost all we have to go off of is a cat who's dead (which you might not even notice until you do a double take, because it cleverly appears like the cat is just curled up) On the one hand, cats themselves play with and terrorize their food without a second thought, so it's almost a comment on that behavior- nothing is "bad" in the natural world, we only assign that to our own actions because of our conscience. There's even some leaves near the scene, suggesting a natural-ness in lieu of the constructed and artificial world of the rest of the picture. On the other hand, it's clearly beheaded the cat in a very non-naturalistic way. Some predators might attack the head, (jaguars, for instance) or start eating there, but they hardly ever pay special attention to separating it from the body. That is squarely in the realm of humans, as it has all sorts of cultural and superstitious meaning you can unpack. Is it some mix of the two possibilities? In conclusion, the blue creature seems to be hiding its deed, as if it feels some sort of shame or recognizes a child's special status or vulnerability to trauma. Is its pudgy little arm at rest, or outstretched, seeking to obscure what's behind it? We still worry for the boy, but there are signs there that give us hope he might be safe from the cat's fate. Even then, how will it prevent the child from coming closer and discovering its secret? Can it communicate? Will it growl to keep him away?
You have a wonderful talent with environments. The primarily purple/blue backdrop makes the creature's yellow tinted coat and especially the boy's bright orange umbrella pop out. This could also suggest being sheltered and free from the horrible elements of the world while you're young.