I certainly appreciate it when people want to know what's on-topic before they ask. Thank you.
That said, we're still trying to determine through trial and error as a community what is and isn't on-topic. So I personally don't think we have enough information at the moment to come up with any clear, useful guidelines.
This is how things are supposed to work. To quote BESW, who knows more about the Stack Exchange platform than anybody I know:
Nah. It's better to assume topicality and define the edges of the Stack's space by what isn't topical, and THAT needs to happen with examples rather than theoreticals.
So as the site gets edge-case questions naturally, it'll slowly figure out the space it can usefully occupy.
If we try to force that, we'll get artificial results based on artificial examples and we'll have to overcome that again later.
And if we try to define the site by what IS on topic rather than what ISN'T, we'll needlessly limit our topicality to only things we can think of beforehand.
It isn't surprising that this is more true on a site about Literature than another Stack Exchange beta. Philosophers have spent centuries debating what literature is. The definition of literature has been politicized to exclude cultures who were deemed inferior. I would say it's normal for a group of mostly amateurs (I count myself as an amateur here) on an internet site wouldn't be able to give an authoritative definition with only a few months of experience.
You're much better off taking a look around the site and seeing what's already been asked. If you want to ask a type of question that hasn't already been asked yet, you can try proposing the question on meta or in chat. Or even better, you can ask the question yourself and see what the reaction is. (If it doesn't get closed, then its acceptable for the site).
Maybe we should consider adding some version of this answer to the help center.