The positioning isn’t a fluff piece exercise - it’s how you define what you are building, who it is for, and who it is not for. As a product guy, it’s your North Star.
Without it you end up doing one or both of going down a tech rabbit hole of ‘it’s a decentralized, federated blah’ and losing people’s interest entirely.
Ideally you should have a quick this is what we do, why we do it, and why we’re different ready at all times - even if your current audience is only true believers.
EDIT: Clicked through to your features page. Confused. Polar allows me to "manage my reading"... oookay. What does that mean? What pain point is that solving for me? Does my reading need managing?
What are the benefits to me as a user? You need to tell this story before you get to the fact that it's based on Electron (perhaps very much not a selling point) and uses PDF.JS. How is this better than Evernote for me, which, based on sheer longevity is probably going to be my first port of call?
Who's your audience? Answer: not 'everyone' - you mention Pre Med students, but then your screenshot has a load of growth hackery stuff. If I'm a med student is there latex support?
Getting out a notepad and making yourself clarify what this is, who you are building it for, and what benefit you see it giving them is going to be a big help for you.
This goes double for you, as you're effectively creating a double sided marketplace of consumers for your product, and sites willing to integrate with your metadata.