Creating the game for the first time and as solo is a great way to learn! I respect for that!
However, I find it too similar to the game called Imago from previous Melon game jam, but since it's your first game jam, I highly doubt you would copy someone's ideas!
Listing some very small problems:
1. The player keeps falling behind the scenes if jumped too high. I had the same issue before, but this can be fixed with using another approach (linear velocity I believe)
2. As some comments state, the player keeps sliding, and it was a little annoying to fall because of that. Additionally, I recommend you to increase the speed of the spark (maybe add that feature in the settings?)
The game could be further improved by adding other entities which can burn and disappear. Not implying that this mechanic should be implemented first, but you could add some!
A very decent job developing this game, and good luck in other projects!