A horror teaser is mostly one person, one doorway and a light behind them. That's the whole grammar, and it's why it works on a single photo. Upload a plain front-facing portrait and you get back a full poster: you standing half in shadow, a sickly warm light spilling from behind, cold blue-grey grade, mist at ankle height, and your title in big distressed serif across the bottom.
Everything in the credits block is fictional by design — invented actors, an invented director, invented production companies. Nothing on the poster points at a real film. Give it your own title, or leave the field empty and see what it names you.