Congratulations on finishing your jam game!
Since this was a basic platformer, I would look into the common ways platformers improve their controls and game feel. GMTK already made a great video about this you should check out.
I also wished there was an easter egg at the bottom of the volcano, a good way to reward the player for exploring in an unconventional direction (although you would then have to worry about players jumping into every hole just to check).