The rules for this game jam are short and simple, but leave some questions.

Manly: How much premade content can you use?

The rules state that you can use premade publicly availabe stuff. This suggests a rather relaxed approach, but what about selfmade assets or even code snippets? Do coding tutorials count as premade code? Other jams allow the use of basic existing code such as controller support.  Is this the case here?

TL;DR Can we use our own existing code snippets or assets?

PS: I am not looking to exploit the rules, just to understand them.

As you said, the rules are pretty relaxed with your own stuff,  you're free to use your own code snippets or assets, but try to stay within the spirit of the jam, so dont just start with a half-built project :) Following a tutorial is a perfectly reasonable thing to do too :)

At the end of the day, its really just about making a game for fun :)