Inception is a movie about making movies.
Cobb is the director. He gets the performances needed from everyone else. He sets the parameters for the job in the first place.
Arthur is the producer. He knows how to solve problems. He knows how the world works. He's sometimes at odds with the director, but eventually follows his lead.
Ariadne is the writer. She's responsible for the setting, the atmosphere, keeping the narrative on the rails.
Eames is the actor. The talent. He plays the roles required of him, starting with the trusted confidante Browning.
Saito is the studio. The money. He's financing the whole thing, and a result, he makes some foolish and difficult demands.
And finally, poor Yusuf is the special effects artist, vitally important but overlooked by the rest of the team (like when the van goes off the bridge and he yells "did you see that?!"...but no one saw it, because they're all still in the dream.)
Mal could be a critic, determined to tear down what Cobb is trying to build.
And finally, Mr. Fisher, the target, represents the audience.