For a 2nd game jam, it's pretty cool that you managed to make a complete game! Here are a few things I would focus on to improve for next time:
- Improve physics and the player controller. For example, make smaller hitboxes for deadly stuff. Tighten the player's controls, and maybe even look into things like adaptive jump height, jump buffering and coyote time.
- Make a better camera. I really died once of twice because of the camera preventing me to see where I was landing. You probably don't want that camera to be 'jumping' with you, you just want it to go sideways.
- Improve the presentation and communication to the player. If you're gonna make a hazard, make some deadly lava, instead of blu-ish water that doesn't look so harmful. If you go for a pixel art game, maybe also make the size of your pixels consistent throughout the game.
That's a few things that I could think of. In the end your game was fun but the game feel could be so much improved! So good job already, and good luck for the future!