I think the gameplay is really unique and has a lot of potential. It sort of reminds me of TowerClimb, and I think the game could work really well as a roguelite.
The main issue I have with the gameplay is that the platforming feels a bit janky. You should consider adding coyote time, a jump buffer, and increasing gravity after reaching the peak of a jump. Another problem I noticed is that when placing a crate, the camera zooms in which looks really cool, but it’s a bit annoying when trying to place crates far away. I’m not sure if this is intentional to limit crate placement range, but if not, it might be worth adjusting. Also, I think it would be cool if crate explosions gave you a small boost when standing nearby.
Regarding the difficulty begin too hard, I think having multiple levels could partially solve this. Most players don’t want to read while playing, so you could start with a really easy level where the player can freely experiment and learn the mechanics. This would also give you a chance to gradually introduce new gameplay elements, such as hazards or collectible boosts, as the levels progress.
You didn’t ask about the art, but I think you shouldn’t scale pixel art. Mixels make the game look a bit silly.
Lastly, I found a couple of bugs in the game.
Here I was able to stick to the wall after blowing up a crate.
Here I got A rank even though I should have gotten C.