Here’s note from Prof. Pelfrey in our module 3 lecture materials that I found encouraging:
If you can write a scene you can write a movie.
If you can write a good scene, you can write a good movie.
If you can write a great scene you can write a great movie.
A movie is usually just 40-50 scenes. Make all of them good and some of them great and you might have some success.
Write on!