Yes!
You can use unity's standard assets, scripts, and build things out of primitives (cubes, spheres, etc) if needed, feel free.
Apologies if the rules seem "loose", its meant to be a relaxing jam. My only rule is that you use atleast 5 of the assets from the mystery box as well as handing in one of your own before the jam starts. But yeah, feel free to use the standard stuff Unity comes it