We all know that in the golden years, as reference for animation, there were live action characters to study movement, posing, lighting, etc. It is all about filling the frame with proportions and personality. Here are some examples for some films, comparing a photostat wit the actor’s performance and the result, showing how greatly they influenced the animators.
Love how they just used a Mickey Mouse plush to reference Michael in the Peter Pan shot.
Many of these actors were favorites and were hired for various characters, like Helene Stanley who was a live action reference for Cinderella and Anastasia Tremaine (Cinderella), Princess Aurora (Sleeping Beauty) and Anita Radcliffe (101 Dalmatians) or Kathryn Beaumont who was for Alice (Alice in Wonderland) and Wendy Darling (Peter Pan) as seen above.