I'm not sure our "role" as spectators and observers is that different from other art forms and would appreciate further clarification about why such a difference requires caution using the term art. Film seems to resemble theatre, but on an other level it's much like visual art, only the image appears to be kinetic, and in another way it is like music in that the editing lends creates a rhythmic component.

Where is the soul (or have it your way, the heart) of the film? Having pondered this for many years, I think the person with the final cut contributes the most to what is obviously a group effort. But that means that there have to be many "takes"; it doesn't work with a low budget film. Next the director, if it's a Hitchcock-type director who also spends most of his time storyboarding. Both director and cutter have to have a sense of how many seconds per scene, how many for changes of POV in a scene, and what I think of as the "relief" factor--you need to follow an intense scene with one that allows the audience to relax and catch its breath. In some movies, of course, the great actor takes over. Despite indifferent cutting and direction, "To Die For" is transcendently Nicole Kidman's. And Kate Nelligan "owned" the second half of "Eye of the Needle." Many of Cary Grant's films would be insignificant without him. (See my piece on Cary Grant, especially the counterfactual on how he would have improved other films): http://www.sensesofcinema.com/contents/books/06/38/cary_grant.html )
I've left out the writer, who in one sense is the most important, but only if he or she storyboards the film. Surely without the writer all the rest of the cast would be out of work (except for some recent movies which just seem to have been made up as they were filmed). Writers are a "but-for" cause, but if I had my choice, I'd take the final cut.

I see that the "html" of my url (above) was cut off in the final posting (what's the preview for? It doesn't tell what the final post will look like)
The complete web address of the Senses in Cinema article is
http://www.sensesofcinema.com/contents/books/06/38/cary_grant.html
Let's see if that works.

I'm glad there was a shout-out (from a caller, no less) to Au Hasard, Balthazar, which I keep telling people is the greatest film ever.