Who is the real protagonist?

In Melville's "Benito Cereno" the roles of protagonist and antagonist are constantly evolving and changing, eventually resulting in ambiguous combinations of the two polar opposites, leaving readers to decide who truly plays which role. In the beginning of the story, readers are led to believe that the narrator is the protagonist of the story, and that Benito Cereno is the antagonist (an insane captain likely to take over the narrator's ship). However, as the story evolves, the roles soon abruptly change. It becomes obvious that Benito Cereno is the protagonist of the story (attempting to escape the evil clutches of the slaves) and that the narrator is just that: a narrator and an onlooker. Babo, on the other hand, is seemingly characterized quite clearly as the wicked and dastardly antagonist of the story, attempting to take over the narrator's ship and manipulate Caucasian people.
It may seem that Babo is characterized two-dimensionally, as merely an enemy and a 'bad guy'. However, upon closer examination, it can be seen that Babo is, in fact, not only the antagonist of the story, but perhaps the protagonist as well. When one reads between the lines of "Benito Cereno", it can be said that Melville does not characterize Babo as a bad person, but merely as a strong person. Subtly threatening Cereno with a razor blade, killing his former master, and attempting to take over a ship aren't necessarily bad things that Babo did, but merely actions that were necessary for his survival. His motives were not after all, greed-based; he only wanted to return home with his people. When Cereno dies and "follows his leader", perhaps Melville is insinuating that Cereno deserved to die for however he may have mistreated slaves (as his leader did). However, this quote is rather ambiguous, as readers are unsure whether 'leader' refers to Babo or to Babo's former master.
Melville could also be insinuating that Babo is the protagonist of the story (and superior to Caucasians) through the quote that the shadow of "the Negro" has been cast over Cereno. While this could be interpreted to mean that the shadow is representative of the 'Negro's' greater intelligence, it can also be interpreted to mean that Cereno feels guilty for his mistreatment of slaves in the past. Cereno's guilt could possibly be the shadow which has come over him, a shadow which is removed through his death as punishment.
While the narrator is most definitely neither the protagonist or antagonist of this story, the roles of Cereno and Babo are continuously changing and becoming intertwined. It cannot be decisively said which character plays the role of protagonist, and which character plays the role of anatagonist.