This is a nice start for a prototype. I had some issues with the controls but then I understood it was mouse based. It lacks some survivals basic things but you can add them later and please do something original not by just eat/shit/build ;)
The game itself lacks some ambiance like sounds but I really liked you models that are effective. If you are thirteen years old the only thing I can say is : Practice !!!! You have so much to learn and to do that you can be a good programer or 3d designer I don't know what you wanna do but PRACTICE buddy !
If you wanna get better, learn C, C++, try to create your own physics and graphic engine, learn OpenGL you will rocks !
And the last thing : GO TO SCHOOL :p maths are really important, as physics if you wanna be a game designer / programmer, many will say you can pass them but getting the basics will help you to improve !
I hope to see you in other jams !
Edit : The last advice I can give you since your are quite young : to not try too hard. This doesn't mean you have to give up on something not at all, but do not try to make the AAA game you ever dreamt of. Try simple project, this will give you the experience. Try small project that you can acheive. This will be more rewarding that trying to get somethign too big with just small pieces. OR try to makes concepts, like special physics environments or fractals, things that seems useless but will give you skills