I wouldn't say I specialize in marketing, but after running an app for eight years, you kind of have to figure it out. Not to say that I'm great at it, but I'm starting to figure it out.
Your use case page is solid, but I'd get more specific. What kind of projects? (Web development? Around the house? Construction?) What kind of notes? (Class notes? Meeting notes? Presentation notes?) The more specific, the more likely to relate. It's tough to create a whole bunch of them, but you could definitely start simple and do some SEO.
I definitely think it's ok to mention features. They just shouldn't be the front-and-center sales pitch. The first step is for somebody to relate "Hey, I could use this!" Then their questions turn to "Will it do...?
I definitely noticed how the shared documents work, but I was suggesting making your home page a shared document that they could interact with. You could start just by creating an alternate home page that's built as a list. That list could focus on really compelling copywriting to get folks to try and interact with it.
It feels like there's a few different experiments that you could try to replace the home page with either use cases or interactive lists. Or maybe a quick animated gif or video that highlights the key interactions?