"The Metamorphosis" uses third person narration. The narrator does comment on Gregor's thoughts, giving us insight about how Gregor deals with his transformation. But, being "outside" as the third person narrator is, the reader has the perspective of the world looking at Gregor as the insect and the world as Gregor himself sees it. The narration eventually becomes more impersonal, reflecting how Gregor's family care less and less for him.
Kafka also uses flashbacks to compare Gregor's current state as an insect with his life prior to the metamorphosis, when he was working and thus, when he was somewhat valued by his family.
The biggest and most obvious symbol in the story is the insect. Another recurring symbol is the number 3, but it is unclear exactly what the 3 represents. A symbol that is vague or containing many possible interpretations is one that is called polysemic, meaning many (poly) meanings. One possibility is the 3 stages of an insect's life. As for the symbol of the insect itself, two contrasting representations emerge first. One is that becoming an insect is a reinforcement of his old life. He felt trapped in a job he hated, manipulated by his family to pay off their debts. Becoming an insect is read literally but it also underscores or dramatizes his previous lifemetaphorically. He is in as helpless a situation as he was before the metamorphosis. On the other hand, becoming the insect is kind of an escape from his old life; an awful alternative but an escape nonetheless. Gregor does enjoy some aspects of being an insect, such as hanging from the ceiling.
The fact that Gregor dies and the family is kind of reborn makes Gregor a martyr, a Christ-like figure.
Another literary device is the mixing of genres. It is presented like a Realist story but clearly has elements of the unreal or maybe even surreal. It is allegorical but the meaning is open to different interpretations. This ambiguity of meaning and blend of conflicting genres emphasizes the challenge of reading this story. Like the polysemic symbol 3, the allegorical meaning of the story and even the style itself are open to interpretation.