In The Adventures of Huckleberry Finn, while Huck may be compared to the Moses, he does not become a "Prince of Egypt," but might we consider Twain a Moses figure who led the enslaved to the Promised Land?
This is a fascinating question, and I suppose we can only answer this by looking back retrospectively and seeing how this challenging text, although it is actually considered pro-slavery by some, actually represented a significant challenge to the race relations and the way that they were perceived at the time of writing. Having taught this text myself for a number of years, again and again I am struck by the way in which it does so much to profoundly shake up and disrupt the way that blacks and whites were perceived at the time.
One way of looking at this text is seeing it as a bildungsroman, a novel of education or of the development of its central character, Huck. For example, we see him at the beginning willing to make fun of Jim and having no compunctions about lying to him to get himself out of trouble when he puts a snake in his bed. However, a few chapters later, after he has lied to him about what happened after they were separated, he "humbled himself" to Jim by apologising, which would have been an incredible statement for a white boy to make at that time.
What is more, in Chapter 31, Huck has to decide between letting Miss Watson know about the location of Jim and protecting his friend. This, to him, is a very momentous decision:
I was a-trembling, because I'd got to decide, forever, betwixt two things, and I knowed it.
When Huck screws up the note he was going to send, for him, he is willing to risk going to hell rather than betray his friendship with Jim, again showing the extent to which he has developed from seeing Jim as nothing more than a slave to viewing him as a fellow human being worthy of the same respect and love as himself. We can therefore say that Twain used this novel to significantly challenge racial attitudes of his time. I don't think we could argue that he was a "Prince of Egypt" figure though.