I'm nowhere near this good at pixel art/art in general so I probably don't deserve to give any criticism, but...
1. The dark outline on the player/npcs feels out of place. I know it's intended to make the characters stand out from the background, but using solid black feels strange when everything else has a grey/colored outline.
2. The pose of the character on the left and the goblin doesn't match the perspective. I think the left leg should be one or two pixels shorter than the right one.
3. Character on the right looks like he's about to fall over backwards. He should be leaning a bit more forward so he's in a more natural walking pose.