I would also try see if the appearance is better when the bottom side has no outline.
All the advice above are very good in general in order to make the character more lively / real. If you'd rather keep it very surreal however, you may rather choose:
- a sinusoid curve instead of the bounce, like a Ghosts'n'Goblins spectre (
https://youtu.be/uIhyjrXVhzg?t=53)
- no squash/stretch matching the movement, conveying is has no mass that would be subject to the law of physics
- a uniform light / not getting light from an outside source
An example of this is the Skel-Monsta from Bubble Bobble, that ignores gravity and walls, and it matches its design :
https://bubblebobble.fandom.com/wiki/Skel-Monstaedit: I had a try
