The overwhelming majority of popular dramatic works, not just musicals, feature one or maybe two prominent characters that the audience innately follows from early in the piece. Nobody ever tells the audience whose story they should follow. Therefore the story and its characters must be constructed in a way that the audience arrives at such an understanding on their own, naturally, without the author banging them over the head with it. Ideally the audience should never know that the process of protagonist identification is taking place. It should happen organically through smart storytelling.
