Cute stuff! I bet there's tons more you can do with the idea. I've jotted down some notes while playing, some of which are feedback, others random thoughts that hopefully inspire.

• As always with jam games, time constraints are gonna be an issue. I'm blown away by the sheer amount of content on display here.
• Unfortunately, some elements definitely received the short end of the stick. Instead of tackling the daunting slope physics with a rigidbody-based character (a tough task to overcome in such a short timeframe) that turned out a bit suboptimally, refining the core game might have been more effective.
• As it stands, the dimension shifting stone seems a little redundant, since you have one already built into your kit. In a larger-scope version of this game, I think it could have good value by means of non-player entities being able to activate them and try to mess with you, but as it stands that's not the case.
• Try to scope down a little and give yourselves more time for polish. After completing all the stages I didn't have enough gems to enter the final one, indicating that there wasn't enough testing. Little things like keyboard-based menu navigation and swapping out the gem counter Text-component with a TextMeshPro-based one in the top left corner would also help the polish of the game. A somber ambient track during gameplay and some more sounds would have also been cool to see... or hear!
• Giving power to the player is pretty difficult to design around. Many games keep the player power level low for a while to unlock a cool powerful ability later on that makes earlier areas trivial. Perhaps locking the F-key away for the first half of the game would allow for more puzzly level design!