Hey there Kay,
Love the art style and assets. Great work! Especially on a CC0 license.
One piece of feedback is that with every model being a single mesh, it makes it a bit difficult to use. For example, I'd love to animate the spikes in the spike tile, but it's all a single mesh, making it impossible. I plan to go into Blender and split it up as best I can, but I figured I'd drop a note about it as I think having split models would be super helpful in the future. I think this applies in general, even to things like the character's large eyebrows and chest ribbon. I'd love to be able to animate and customize some of these things, but it's difficult in a single mesh.
I also plan to go and and rig & skin the character models, and as amazing as it would be to have characters rigged ahead of time, I understand it being a fairly big chunk of work.
Again, awesome work, and thanks for contributing these assets to CC0!