That sounds like a great launch, actually. Most projects on Itch will probably not see those kinds of numbers in the first day or two, if they ever do.
That said, maybe a little taste of the rules would help. Reading your page, I understand that it's an investigation-themed, rules-light system with a three-act structure and some promised innovative mechanics, but that doesn't tell me a lot. I know you don't want to give too much away since it's only 13 pages. What if you wrote up a short, fictional "transcript" of a sample session, like a few paragraphs showing how the end of the first act might play out, and gave that away for free? That might help players get a better picture of how it plays, and it should be easy enough to do.