Not looking to argue against the rules, just wanting clarity on what sorts of assets we're specifically not allowed to use which are not made by our own hands during the duration of the event.  I imagine obvious stuff like map layouts, text, characters and stuff that makes a game unique from another but what about models, sprites, textures, etc.  or sounds or music.  Obviously engines are probably acceptable, but what about code?  Would it be possible to use existing code for like for example platforming, dialog systems, etc?  Maybe more difficult things to get right like fonts?  Does it differ if it's our own code we made prior or if it's something acquired from an asset library/store?  Or is the expectation just new project in our engine of choice and everything put in (logic/data/visuals/sounds/music) is by us individually within that period of time?  I'm fine with it if that is the intent.  I'm not used to what is typical or common precedent for game jams as this is my first.

If something is on an asset store or is a stock asset, it's fine to use (if it's a paid asset you need to have bought it). If it's public domain then it's all good. If it has a creative commons license then just follow the terms of the license and you should be good to go. Main thing is don't use anything copyrighted, stolen, or ripped from other games. Existing chunks of generic code not specifically made for your submission, like dialogue systems and player controllers, are fine to use.

With all that being said, it's encouraged to do as much as you can yourself and within the submission period if you're able.