I have a kid who's seriously considering making a game in Scratch just so she can join in with her older family members.  If you make a submission, you should be proud. 

I did my first jam a month after starting unity. With quite ok results. 
Keep it simple and focus on what you already can do and you will be fine. 

A simple game with good polish is far better than a complexe one roughly put together. 

There is one thing I know for sure, once you have done it, you will be happy you did it.