mann im sorry but i gotta be honest its really beginner level
heres a few things you could do:
- create or generate a pallet of colors for the art, then draw using those (theres free generators like coolors.co)
- make all of the textures with the amount of pixels proportionate to the size of the object you have in mind
- look up pixel perfect art in unity (or heres one nice video www.youtube.com/watch?v=5jbgT25fc-0&)
- make smoother controls (something like this www.youtube.com/watch?v=whzomFgjT50)
from there just watch some tutorials like brackeys and most importantly experiment
good job joining the jam tho, continue working and youll get even better