Captain Amasa Delano is the focalizer of Benito Cereno, which means that the reader experiences the events of the novella through his subjective perception. In other words, Delano is the character on whom the narrator is focused, and every single interaction in the text is filtered through Delano’s point of view.
The captain of a whaling ship, Delano is initially presented to the reader as a relatively intelligent, established, well-balanced individual who is guided by a keen sense of morality. However, as the novella progresses and the situation aboard the San Dominick grows stranger and stranger, readers come to see that Delano is less of a reliable narrator than one would have originally thought. Delano is exposed to a number of very odd events and behaviors during the duration of his stay aboard the San Dominick, but he does not do anything about it himself. He remains contemplative, sometimes politely inquisitive, where most men would immediately question these events vigorously or take immediate action. Delano continuously second-guesses himself, and his attempt to uncover the truth on his own is ultimately thwarted. Delano only actually finds the answer to the enduring mystery of the San Dominick and its crew and captain when Cereno leaps into his boat and reveals that the slaves, having successfully rebelled against the Spanish slave traders, are actually in control of the ship. By being so passive in his observations, Delano remains in the dark until all is revealed to him. However, this passivity is what allows Delano to stay alive, as Babo almost certainly would have had him killed if Delano had begun to realize what was happening aboard the San Dominick.
That said, Delano’s passivity is only part of the reason he is unable to see the truth; the other is his inherent racism. It’s clear Delano does not think of himself as a cruel man, but he adheres to a rigid and narrow-minded understanding of race and people—that Black people are inherently inferior to whites, and their subjugation is part of the natural order of things. Because he cannot conceive of a possibility that doesn’t align with his worldview—one in which Babo and the others are intelligent, calculating, capable, and desperate for freedom—he ignores obvious clues, positing theory after theory to account for the oddities he witnesses but never considering the truth as a possibility. That Delano is easygoing and good-natured while also clearly possessing dehumanizing beliefs about Black men and women highlights the prevalence of these beliefs in the American consciousness, even in people like Delano who aren’t cruel outright.