I also value Joseph Campbell’s work. Hero With A Thousand Faces remains the best book about storytelling ever.
I call it the “Save the Cat” scene. They don’t put it into movies anymore. And it’s basic. It’s the scene where we meet the hero and the hero does something — like saving a cat — that defines who he is and makes us, the audience, like him.
The number one thing a good logline must have, the single most important element, is: irony.
The second most important element that a good logline has is that you must be able to see a whole movie in it.