The theme is not a requirement, more a suggestion.
If you think there things you can do to improve your game, and you want to do it, then do it.
There's no real prize for winning, just as there's no real penalty for losing.
Your game is your creation, you can do as much or as little as you want.
I would always aim to submit, so long as I have a playable build. I find doing these jams is about the experience of making a game, and getting feedback that can help me focus for the future.
Good luck!