In the play The Glass Menagerie, are the characters failures just because they didn't reach their goals?

Your question presumes that each of the characters had a
goal and that they either clearly did or did not reach those goals. Let's see if that's
true:

Amanda's goal for Laura seems to be to help her be
self-sufficient, either through a career or through marriage. In the end she has neither
a career nor a husband. Is that failure?

Amanda's goal for
Tom is less clear, as she relies heavily on him to achieve the goal for Laura. What is
the goal?

Amanda's goal for herself is buried in her
ambitions for her children. Does she succeed?

Tom's goal is
clear from the start--to leave his miserable life and be free. He succeeds at half the
goal; does he succeed at the other?

Laura's goal seems to
be to avoid most human contact, which she does until Jim arrives. What happens after
their "date" is not as clear.

Jim's goal is more like his
ambition--to be more than just a shoe warehouse foreman. Does he make something of
himself?

Think about those questions, and once you have the
answers from your own observations and perhaps some class discussion you'll be able to
write your essay.