You've done a good job of avoiding overdithering and working with a limited palette (it could have fewer colors with minimal losses, but it's still pretty good) but the things with the black outlines are where the problems are, I think. The water darkens the pillar way more than it does the background, I'm not entirely sure what the enmy is (this would probably be helped with animation, but as-is it looks like a snake hatching from an egg with eyes) but most of all I can't tell for the life of me what the main character is doing with his arm. I feel like you miight've been trying to have his shoulder really low down and his hand by his face, but that part of his arm and body are trying to blend together to make it look like his arm is going backwards.

Hopefully that made enough sense, my computer's running too slowly right now for me to try and reword this ^-^;