Is this one of your first jams? It's totally normal for this to happen, especially if it's one of the first times you're participating in a jam.
Over time, you'll develop a better sense of what you can create with your skills during the jam period.
And don't worry if you can't submit the game for the jam, even if you haven't submitted, you've definitely improved some skills in these last few days. Or perhaps submit what you've managed to create, and then work on the project for a few more days, but don't invest too many days, weeks, months, invest just enough to deliver the idea you had for the jam.