As somebody who also made a top-down 3D shooter in Godot (with a very different vibe), I salute you. The concept here was hilarious and goofy, reminds me so much of something you'd see on the NES in the 80s, although of course the gameplay was much more modern. Extremely frenetic and chaotic, but a lot of fun! I can't believe you managed to implement customizable character design in a game jam. The actual gameplay was almost too fast-paced and got extremely challenging in the later waves, but I did have a lot of fun with it and managed to beat the boss.
It might help a little bit to make the enemies stand out more from the ball pit, although it's difficult when you're using so many different colors, I'd imagine. I also felt like the music was a bit too loud by default, but that was easily fixed with the settings menu, so good job on including that.
The expression of the theme was great, you hit it on multiple levels. The prequel memey spin move was fun, ducking down to reload and hide was a good mechanic. I also love dodge roll type dash moves, but everything felt so fast that I rarely had time to use it. It felt good when I did though.
Anyway, cool game and nice work!