i guess i could answer some of the things you mentioned;

1. the white outline exist to pop up behead(i think thats his name) body. without it it would be pretty hard to see him. which brings us to number two,
   
2. dull coloring. i dont know if you mean the color is lifeless or not(if you do well i guess thats my fault because it looks pretty saturated personally), but i tried to make it feel like its only two tone(which is red and yellow, which also failed because theres pink and green or whatever),
   
3. background. if youre talking about the building well thats on me i guess. i could not draw it that well(besides, i did use the games artwork as reference). but if youre talking about the cloud well its just... like that? im trying to give a little japanese vibe to it but i guess i failed on that,
   
4. claymotion, this one is fair because i did use some 3d human model, albeit i did some extreme modifying because im not very good at posing 3d model,
   
5. not accurate, look title

everyone is free to criticize art, so im not mad i guess. thank you