If you really want to join, you could try scratch.mit.edu, it's a block-based coding platform that's pretty easy to pick up and teaches programming fundamentals well in my opinion.
I've been wanting to join the jam as well however time got the best of me, and I procrastinated on learning Godot/GDScript and barely know Unity/C#, so it's actually the platform I'm going to use until the next jam, where I'll hopefully have gained the experience to work somewhere more advanced.
As for assets, you can look for royalty-free assets online, search for ones on the platform itself, or just do the best you can!
Either way, I'd encourage you to just practice! That seems to be the best way you can really learn from my experience.
Viewing post in not sure if i should really participate
That actually gives another reason for Scratch, it runs entirely in the browser, and trust me any assets you leave downloaded (if you don't just just paste them into the editor and let the servers handle it) won't take up that space. And for advanced work, things like LÖVE or Godot should be pretty lightweight. I would advise you maybe look through your storage at some point for good habit anyways, but you're not without options.