There's a lot I like to talk about this demo that I won't put in a simple review, haha. I'll try to keep it short here: 

It's a great game so far, it sure needs some tweaking, but with the variety of abilities, it's an enjoyable game.

To be honest, the graphics are a bit on the low end, but there's a lot of unique animations and love/effort put into them that I find it making up for it.

The growing abilities are great, gaining access to the dodge roll so early is quite interesting considering how much of a mobility tool it became. I like that one, the limitation of air tricks is a nice touch to keep it limited. You could prehaps abuse it to avoid enemies constantly, but not fighting them puts you at a risk of not collecting enough stars.

The elemental abilities are also awesome, I like to think you can do some fun synergies with them in later levels, leaves up to some fun speculations.

Camera movement does feel a little bit choppy, most notable when it's moving towards other sides. Perhaps a little transition between rooms may help as well.

Overall, a very cute and great looking game, I may have a huge platformer-gamedev bias, but I just find it impressive in what you've pulled off so far, keep it up and go for it!