“If you string together a set of speeches expressive of character, and well finished in point of diction and thought, you will not produce the essential tragic effect nearly so well as with a play which, however deficient in these respects, yet has a plot and artistically constructed incidents. … The STORY, then, is the first principle, and as it were, the soul of a tragedy.”
(Poetics, Part VI)
Let’s go ahead and put too fine a point on it. Whether we’re discussing tragedy, comedy, movies, jokes, commercials, any form of narrative, Aristotle’s Guiding Precept #2 is simply:
THE MOST IMPORTANT ELEMENT OF A SCREENPLAY IS THE STORY.
If you have to go to sleep every night chanting to yourself “story, story, ...