Woah, this is incredible! I was a bit unsure where it was going at first, but once I made that first connection to another square (great foreshadowing in the intro sequence, by the way, love that!), it all suddenly made sense! Not only did the platforming feel responsive and tight, but the puzzles also complimented the movement really well, too! I liked how you stuck to a minimalist style (quite similar to the original Pico-8 Celeste), and only used small sprites throughout the game. This really helps to create a cute and somewhat eerie atmosphere for you to discover. Again, the puzzle mechanic worked super well and I think it was a fantastic implementation of the theme and geometricness!
I did find the jump sound effect to be slightly repetitive and harsh, so I'd suggest adding a bit of randomness to the pitch every time it's played. Even a small +- 10% whenever playing the sfx breaks up the monotony and keeps the player a bit more engaged. And obviously with some more time outside of the jam, you could include some tunes and more details to the world, such as different colour flowers, mushrooms, small critters, and snowmen :P Overall, I really, really enjoyed this and like you said on the game page, I would love for this to be worked on more! Amazing effort for your first jam game! :D