I'm so glad you decided to upload! I think you should be very proud of having made something playable in such a short time, and I think you have a great foundation to build on here. The mechanics work great, and you even have animations! I agree that starting in an area where switching between worlds was safe would be an improvement, just to get the hang of things. But I had fun playing and I think short levels suit this kind of gameplay (my jam game has a similar mechanic and I honestly wish I'd made my levels shorter).
Good work and I'm looking forward to seeing where this idea goes!