Here's why the raven's identity is ambiguous:
* No name or backstory: The raven is never given a name or any specific personality traits beyond being a black bird.
* Voice of the narrator's grief: The raven's single word "Nevermore" echoes the narrator's own feelings of hopelessness and the impossibility of ever seeing his lost love Lenore again.
* Symbol of the unknown: The raven's presence and its ominous, repetitive response can be seen as representing the unknown and the inevitability of death and loss.
Instead of focusing on the raven as a character, the poem explores the psychological state of the narrator as he grapples with his grief and the raven's presence further amplifies his despair. The raven acts as a catalyst for the narrator's emotional journey, but its own identity remains shrouded in mystery.