I know that I will comment on an OST when I start thinking "there's no way this peep started to compose this before the time limit!". Assuming that you did - this is not an OST for a jam, this feels like a finished work for a fully fleshed out game.
Centipede Caverns is a song that carries so much personality, you almost didn't need to title it. I personally love clunky instruments with texture. Using them takes skill and patience since they are full of detail, but you created a theme with them that feels whole and precise, like the dancing notes take breaks to allow the player to slash enemies in a lonely and dangerous environment.
Evergreen Valley is such a living tune. The composition, the marimba protagonist, the sickly wailing background synth, it is excellent. I like how the tune starts sad but shifts to playfully ominous. It has all the traits of a true theme.
I personally wish the rest of the OST would have had more of oddly sounding instruments like the two tracks I liked, but if I were a judge, those two tracks would be finalists.