No, it wasn't just you - balancing has always been one of my weaknesses, and this jam was no exception. Sure, the first 3 rooms of actual platforming are easy enough, but I kind of got carried away after that. The last room in the game has such an absurd timing window that even after beating the game 5 or so times I can't help but die to at least 15 times, so maybe it's best you didn't get to the end :'-)
I mean, I did try to introduce concepts slowly, but then I thought "oh, wouldn't it be cool if the player went over there, then there", which followed by some skip-fixing, led to an incredibly unbalanced game. I'm sorry you had to be subject to my bad balancing :-/
(Celeste isn't nearly as badly balanced as my game, you should give it a try!)