Overall a solid, complete game OST that spans the entire story, so great work there! I love some of the musical ideas you've got going on here, and I think your instrument choice fits into the fairy-tale world you're describing very well. I absolutely loved the slightly low-res voice samples (especially in the Shop Theme,) they gave me a nostalgic SNES vibe. Town, Shop Theme and Defeat are all short, sweet, and to the point; they fit their intended purpose well.
I think you had some great ideas here and definitely some budding talent as a composer, so my highlights below are intended to help you build on those solid foundations for future musical endeavors. (In other words, I'm dropping you a wall of text in hopes that it is useful to you!)
My biggest advice would be trying things like: adjusting the release time/making the notes fade for the longer chords. Especially for Foolish Wish and Town, the organ and accordion-esque sounds feel like they are a bit overpowering as they turn on and never really stop, especially in Town where the accordion creates some dissonance with the other instruments playing towards the end of the bar. Having them fade into the background a bit at the end of the note could help break up that "constant wall of sound" and give the rest of your instruments some room to breathe.
One thing that I've learned over many years of practicing composing is often times, less is more. This applies in two ways directly here; the first being choosing your notes carefully. It's tempting to just fill out your piano roll with tons of notes, but rests can be just as important. Said a different way, the less notes you have, the more impact each note carries. In your Boss Battle theme, you've got the right idea by slowly introducing in some instruments and then dropping a couple of them out to create a sort of breakdown segment. It breaks up the monotony and keeps things interesting, very well done with that. But towards the end, there's a lot of things playing at one time and things get a bit jumbled up. You could fix this by removing some notes, but there may not be anything wrong with the notes you have in this case, so less is more could be applied a different way: volume automation.
Turning the volume down of the notes that are supporting to let the lead stand out more will draw the listener's ear center stage to what you are designating as your lead instrument. Part of the music production process is making those hard decisions on what to turn down and what to make loud, especially if you're like me and think "but ALL of these are important!" Regardless, making good decisions here and highlighting the lead parts of your track will make the piece come together much better as a whole. In addition to volume, EQing out frequencies that aren't important to a specific instrument will also achieve the same result (though the necessity of this varies a lot depending on the samples and source material of your instruments.)
Some other reviewers commented on the general impact of your battle themes, so I'll keep this part concise: Raising the tempo, adding some more action/variety to your drums, swelling certain instruments in different areas, adding more tension, etc are all techniques that can be used to add to the impact of the track. Compositionally, I think your Battle and Boss Battle themes both have solid foundations and are definitely headed in the right direction. I would encourage you to play around with them some more after the jam, practicing how you can change them up in beneficial ways. This will prove highly beneficial to you in future compositions!
I look forward to seeing what you come up with in the future!