Hey Arowx! I wouldn't suggest submitting if you can't hit the 500 character target, since that's the stated purpose of the jam.
However, something that I've done myself in the past if I'm at a wall and can't quite get an entry to 500 characters is to create a separate branch of the project, remove some behavior or objects, and submit the stripped-back version that hits the character limit. That way you can at least get your entry in (if it loads and is semi-playable, it's likely as sturdy as 50% of TTJ entries), but then you can take the larger base you built and run with it in other ways!
Hope that's helpful! And good luck!