I love the world you created and all the different characters were a joy to discover and talk to. The Cactus Guard were my favorite lol. And I appreciate how well you incorporated the Ecosystem theme.
Being able to buy the abilities and access each area in any order is a fun idea, but also kind of a double-edged sword. The nonlinearity and player-freedom is great, but it's hard to level design around not knowing what abilities the player has at any particular moment. So there was maybe more backtracking than there needed to be through mostly empty levels. ("Empty" meaning I've already talked to the NPCs and collected most of the pickups)
But it was still very fun to get new abilities and explore more and meet new characters. I had a great time!