Came back to it and beat the game. I found that using the arrow keys wasn't viable because if you hold UP and LEFT at the same time, pressing Space doesn't do anything. Switching to WASD works, but then I kept trying to press Space to jump instead of W because that's how games almost always work. Ended up using WASD with my right hand and and crossing my left hand over to hit the spacebar, and that worked.
There's a lot of potential here, but between the awkward control scheme and the fact that you arbitrarily can't ground pound until a little bit after you start falling from the peak of your jump made it feel like all of the challenge of the game was fighting against the controls rather than the actual platforming itself. A lot of the gravity switch parts also felt like trial-and-error as it didn't give enough time to react on the first try. It also wasn't very clear what you are supposed to do against the boss, though I did like the concept of the boss mirroring your position.