Filmmaking has, and always will be to some degree, a collaborative process (note I did not say “art” because not all film is considered “art” even by the filmmakers themselves).
Which is why I never understood the underlying reason for developing the “auteur theory” (https://en.wikipedia.org/wiki/Auteur_theory) in the first place. Or this preoccupation with who is the principal author of a film (or the writer – because in film, the writing while essential is simply the beginning before a billion things in production and post-production happen in transforming 100 pages into a images and sound).
In reality, as just about anyone who has worked on a film will know, it involves everyone’s creative input and contribution, even on the most autocratic projects. Everyone has their fingerprints in some way shape or form on the final cut of that film. And every film is different in terms of which aspects or departments have the greatest impact or signature on the film itself – in some, it’s the cinematography; in others, it’s the production design; and in others, it’s barren but an actor’s showpiece.
Directors are not auteurs, at least in my experience. They are more like conductors of an orchestra – the glue that binds the collective performances and contributions of the players. And the music itself isn’t about the conductor or even the composer – but about the music itself and its effect on the audience.