This is a nice, solid platformer! I love the simplicity (dare I say, minimalism) of the project, and your music + sfx work great together! I won't critique too harshly since you wrote you didn't spend much time on it (and hey, fair enough!), but I would love to see some more mechanics to make for some more engaging gameplay. Things like moving enemies or rotating spikes would add a new dimension to how the player navigates levels, and maybe even some puzzle mechanics such as buttons or levers. I'd say the aesthetics work really well and you did a great job selecting complementing colours for the levels, and I'd recommend some animations for the player to make it feel a bit more grounded in the world. I'm a big fan of squeeshy animations but feel free to play around with what you feel is best :P
Always love to see a platformer in game jams and you pulled it off pretty well! I do hope you continue your development on this game and I look forward to any updates you may give :)