what is the universal thing in the metamorphosis?

I think this is largely a thematic question. I think alienation is one of the larger themes we can relate to. Before his metamorphosis, Gregor is alienated from his job, his humanity, his family, and even his body, as we see from the fact that he barely notices his transformation. Similarly people, at times in their lives, can feel so alienated that they don't notice how they are living or acting.