To elaborate on some of the items others have mention, here are head counts for Pixar's most recent film, Elemental, based on the credits on IMDB:

    1 director
    3 writers
   20 voice actors
    5 producers
    1 music composer
    2 cinematographers
   12 editing
    5 casting
    1 production designer
    2 art directors
    2 production managers
   14 art department
   42 sound department
   85 visual effects
   68 animation
   46 music
    1 continuity
   77 additional crew

That's 387 people. These kinds of movies take years to produce (7 for Elemental), although not everyone works on them full time during the full length of production.