Very lovely little platformer! I really like the pixel art and music, very nice use of the theme.
A few feedback I have is you probably want to show where the player's going since most of the time, when you jump/fall, you just don't know where the character's gonna land and just have to hope you don't hit spike, maybe zoom the camera out could work great. There's also time when you get too big to get out of certain places and there're no spike to damage yourselves and restart the levels, you kinda just stuck there.
Just a few tips I wanna share, hope it can helps, I heard this was your first jam! Congrats and very impressive work! Great job!