My guess is that Model is a stand in for the actors to interact with. The full body will be CGI (much like Hulk)

One article brought up the theory that if all films were to revert back to Marvel, they wouldn't have enough time, effort or budget to get all these films made.

By having different studios handling different films simultaneously, we can have more of them, which is why we can have Guardians, Avengers, X-Men, Spider-Man and Fantastic Four in such short periods.