Musicals include every person's voice and their voices are incorporated in to one song that is trying to tell some form of a story. It wouldn't be a musical if there were one person right? So the "collaborative" part induces the fact that it is a musical with multiple roles for singing and acting. I hope this will help you, this answer came truly from me. Thank you.
Musicals are a way that any group of people are able to collaborate to put different personal talents and qualities together wether that’s singing, acting, stagecraft, etc. Into something visual that anyone can enjoy
