Excellent game!
I loved the graphics and the level design, you took a lot of great decision to make it fair and possible to beat. Sticking to the ceils is really clever and adds a lot to the platforming. The artstyle is beautiful, you chose the colors nicely and the spritework is incredible. I'm just missing some sounds or music.
Take this paragraph as my personal opinion. I understand why you chose to make the jumps so slow, It's a necessary mechanic for completing the stages. It allows the player to jump without needing a platform but just mastering the timing of the animation in the air. I consider that in terms of design there's nothing wrong with that decision, but in terms of feeling it creates the sensation that there isn't enough control of the character and slowens the pace of the whole game when there are just two sections where its use is compulsory. I think there are better solutions, like a pressing and releasing system (charge and then jump) or simply a double jump.
You did an great job, keep making games this good!