I had the same idea for a jam, only we couldn't make it happen.(
Worry not. It takes some time and experience, my first game jam projects were much rushed and I couldn't keep up with the time. After doing it for a while you start to get all the experience you need. And remember there's just so much many jams and you can even make a full project with deadlines, that really helps with the time management, which is a skill you (and I, slowly) develop over time. Best of luck!
Hey. I hope you are doing well. You don't need to worry as sometimes things can get out of your hands. But what you need to remember is to keep on trying. The GMTK Game Jam is only one of the thousands of game jams. There are a lot of other jams to show you talent! Just don't worry about what happened and think of the future. I am sure you will be successful :) And hopefully, wish you will make great games. Don't forget to share our project with your other friends on Itch.io. BEST OF LUCK :)