A fun & lovely little game! I was a fan of the ending in particular.
The way the frames pass by make it a quite slow-paced platformer, which is a bit perplexing at first, but has its charm & we eventually get used to it. The music contributes to set a relaxed mood :)
Still, some of the harder levels can get frustrating, so maybe making the frames switch faster, or making them controlled by the player would have been more comfortable.
Other than that, how you turned the "getting stuck in walls" thing into an actual mechanic is a great idea.
I also would be interested in reading how you implemented the smooth frame transitions.
Nice work once again!