Not 100% sure I'm gonna join yet, but just wondering what assets can or cannot be used. Like, if I draw something myself, does it count as free? 

well, yes, since it's handcrafted :)

depends on context. If you make it pre-jam it's okay if you a) let anyone who asks use it or b) you make it freely available online. If you make it during the jam it's okay no matter what.

Cool, thanks. While we're at it tho, how historically accurate should I aim to be here? Wanting to figure out the boundaries before I try to brainstorm.  

Like maybe I can't include fantasy elements (e.g dragons/wizards exist!), or maybe I can't  make romance games with real people as love interests, etc. 

it depends. you can do what you want, but there's a historically accurate rating category so don't go too beyond the pale

Alright.