If it's your very first jam, and you literally have no experience with game logic I'd suggest you use : microstudio.dev
It is a nich, web hosted open source game engine that has the bare necessary features for doing game development.
If doing everything by hand for someone starting gamedev sounds like a bad idea and you'd rather start with something with a lot of premade components for you to use, then you fell into the same trap most gamedevs amateurs (me included) fell into.
Long story short, if you do not know game logic nor how premade components work under the hood, when it comes time to debug you will be in hell.
I know almost nothing about shaders, so if microstudio doesn't give you the tools you want to make your game, I would suggest going with godot over unity simply because it's lighter and got much better doc.
Even then, before the actual gamejam start, messing around with microstudio to understand the basics of gamedev would only be to your benefice.