Should I quit the school play?

Hmmmm. A director would never corrupt a play and put an actor into a part that is not well suited for them. The problem is that you may have not been suited for some of the parts but it seemed like you were suited to be a mermaid. To do acting you must adapt to all situation around you, there are a few actors backstage that may annoy me but I ignore them because if I get mad at them it will take away from rehearsal time. If someone is bothering you, tell them to stop, its only one word but has alot of power like "no." As people said before there are no small parts but small actors, every part is important to the play, if a background actor doesnt do their part, it could mess up a scene. Deal with the part, adapt to it. Most actors think its about the words, its about the movements and the emotions that run through you when you are on stage. If you are a mermaid then you must do you research and try to help tell the story about the play.

I hope you sta, it would be aa very good experience.

Then, do what you feel like.

Why listen to that ***.

If you're really as experienced as you say, you shouldn't have to put up with this ****.

Perhaps you simply screwed up auditions.

Though, perhaps you aren't the best.

I mean, at my school, I'm widely regarded as the best actor, despite the fact I've never done any kind of training, while there are people who have been in big musical productions and stuff. I simply act by instinct, and always land huge parts.

Remember, the director put you there for a reason. If he thinks you'd be good there, you would be, or else he's a retarded *** director, and you probably shouldn't work with him.

Anyways, best of luck whatever you do

Look, you're doing a musical. Thats not your area of expertise. In order to get a good part on a musical, you need to be able to sing, act, and dance. And based on your question details, you can only do one of those three (and not even in the right style), so I'm not sure why you even expected a large part because theater acting isn't the same as film acting. Usually for school plays, the casting is based almost entirely on who can handle the singing because thats the most prominent part of the show and the audience will notice if its terrible. Basically, for theater, you need to be able to sing, dance, and theater act (what I was talking about with styles above), and I'm not guessing that you sing or dance and you film act not theater act, theater isn't your area of expertise at all. You can't bundle all acting into one. But you should do the play to expand your horizons and for professionalism purposes.

There are no small parts.

Just small actors.

Quit if you want but if you are so "experienced" you can perform any part well without any lines.