I'm currently working on a game which I believe it's near completion and I've been trying to push it through, which I'm unsure whether I'll manage to finish it by the end of this month but perhaps by February.

I would of course direct to a demo or something of the sort if I don't manage to finish it by the end of this month

You should still be able to submit something yes, either a demo or a beta  version of the game.  You can upload the game so only those with the link can see it, which would just be people rating games in the jam (if you're worried about making it public in an unfinished state).  Then you can get some feedback and continue updating it after the jam.