Each visual arts element has certain function or characteristic, but why sometime people still have different interpretations, when they face the same piece of art?

A theatre comprises many people’s efforts, but people may have various interpretations to one theatre, no matter directors, designers, or even actors. So are audiences still able to comprehend the original meaning that playwrights want to express?

Throughout the whole play, Valentine keeps saying that Gloria inspires him. But on the other hand, Valentine also influences Gloria. At the end of the play, how is Gloria’s characteristic different from that at the beginning? How does Gloria change?