Don't let me take away from the fact that you made a really amazing first game! Just trying to give credit where credit is due... I've been dabbling in game development for around 10 years and your first entry is much better than probably about 90% of the prototypes I made in the first 8 years of dabbling... only starting to get half-decent at game design now. So keep learning - I expect to see great things from you in future jams! :)
I stick to 2D for the same reason (not fast enough or good enough to do 3D in the time given for jams). Until about a year ago I couldn't even reliably make decent 2D programmer art on jam timescales, so I used to use pre-made free assets in jams. Jams like Ludum Dare usually let you mark a category as N/A to indicate that you didn't create that part of the game, but I don't think Itch has that option.