There is often a box on an audition form that reads something like this:
I will accept any role offered YES  NO 
(If no, please explain)
I am firmly in the camp of accepting any role. Perhaps the opportunity being offered isn’t what you’d hoped for or believe you deserve.
Accept it. You don’t know your future path well enough to predict where this opportunity will lead, and turning down an opportunity comes with several significant downsides, including alienating the director, separating yourself from your peers, losing out on a musical/educational experience, and more.
The disappointment of not getting the opportunity you wanted is hard. Face it head on and don’t compound it by removing yourself from the experience. Be brave, accept the loss, and move forward, making the very best of the situation.
The hardest part of a performing arts teacher’s job is without question the audition process–making choices from within a pool of students you love is gut-wrenching. Trust these educators are doing their best to support their students, including you, and accept any role offered.