You might find answers to your questions by examining the relationship between Benito Cereno (Don Benito) and Babo. Remember, after Babo and the slaves are captured, Cereno succumbs to “melancholy.” He refuses to testify against Babo. After Babo is put to death, Cereno dies. According to Herman Melville, Cereno “did, indeed, follow his leader.”
Considering the above, you might argue that Melville conveys the idea that the link between slaves and masters is unbreakable. Their destiny is one and the same. When Babo dies, Cereno dies. Their afterlife is joined. You could view Cereno and Babo’s relationship as a warning about slavery. If people don’t want to be irrevocably tied to slavery, perhaps slavery should cease to exist.
More so, you might say that Cereno is Melville’s way of conveying the idea that in the end, masters become slaves. You might think about how those with slaves become slaves to their slaves or almost entirely dependent upon them. Without them, as Cereno shows, they’re nothing. As the ending seems to suggest, the slaves, even in the afterlife, are the real “leader.”
Regardless of what Cereno’s and Babo’s relationship might theoretically say about slavery and its lasting power, in reality, as your question notes, it does seem like the “victors write the history.” In the end, the people that permit slavery determine the narrative and fate of Babo. They sentenced him to the afterlife. They, in a sense, wrote his history.
Sure, Cereno died as well; yet Cereno wasn’t sentenced to death. He died of natural causes. Again, regardless of what Cereno’s relationship with Babo might symbolize, Cereno was not a slave. He was a free man. The victors did not write his history. He departed for the afterlife on his own accord.