Fun game! I like the world-switching mechanic!
One (subjective) tiny nitpick I have that I think could add some extra polish to the game: There were a couple of moving platforms that would start their cycle in a position where you have to wait a couple of seconds for the platform to come back before jumping on it. I think you could have their cycle start in a position that gives the player time a little more time to jump on it the first cycle or maybe have the moving platforms preserve their position even if that world isn't currently loaded could address this.
All in all, a very solid idea and implementation, especially having been your first game.