Had a lot of fun with this one!
I enjoyed the metroidvania-ish idea of collecting movement upgrades for your island to slowly allow you more and more to explore/more freedom of movement.
I think my only thing is that even with all the obvious points towards 'Start with the ocean/stone, and work your way into the propeller upgrade' my brain still went towards wanting to get the floating islands first (especially since there was one that looked particularly cool at the beginning).
Overall, liked the boss/area variety, liked the islands having different more likely resources (purple=enemies, ice=iron/rock, ocean=rock, forest/grassy=wood) since that helped with late-game collection, and liked the development of movement to help with the mysterious story.
Some small critiques I have are:
*I wish the snowball enemies appeared more than once (maybe one in the cave-y formations)
*I wish the plant enemies were more obvious from the beginning. Was not too bad, just confusing at first. Same with a difference in iron/stone.
A great job! I look forward to more content from you in the future!
EDIT: Can't wait! I liked a lot of your other work, as I mentioned on Temple of the Four Serpents (Amidst the Sky, Soul Mirror, Warper, etc.)