A primordial Gary-Stu - or a parody of one?
Conneticut Yankee is a hot mess that most likely has no clue what it wants to be: Satire? Parody? Manifesto? Attack at Romanticism? Attack at American South? Attack at church - Catholic or in general? Attack on contemporary economics? The tune changes with author's mood - but this results in cacophony rather than a complex symphony. It has not the quality of belles lettres to pass for a work of art high enough to need no other merit; the narrative is the one of a reminiscing methuselah, meandering and inconsistent, full of digressions, unnecessary details and embellishments; humour is too topical and dated to withstand the test of time, and too mean-spirited and full of personal bias to be taken as a serious critique. Most of the arguments have too shaky foundations for me to even consider agreeing or disagreeing with.
Don't be misled - this is not about a fish out of water or a culture clash; this is Twain flinging bile at medieval England (or perhaps, simply, England) in general, choosing to cram the entirety of ten centuries into "dark ages", equaling post-invasion world of Ivanhoe with Arthuriana. And then he decided to stir in parallels to South and preach about his ideal world order while he's at it. It could have still worked, were it but better thought out; but even for a work of fantasy, all plot contrivances in Yankee require too much of suspension of disbelief. Few decent arguments are weakened by digressions and trivialities. In desire to cut straight to the subject of the mockery, we get informed that technology necessary was developed, without any foundation. Narrator is also headache-inducing; he might be unreliable, but it's not clear. If he is unrealiable, why make him be the one to voice arguments you want heard? His egoism eventually goes over the line, making Hank just as hateful a character as the slave-driver.(show spoiler)
It could very well be this was the intent, for he does some undoubtedly wrong things; but the general inconsistency, particularly the fact that he often serves as author's mouthpiece, really does not allow me to form any solid judgement.
And that's not even touching the elephant in the room; rave against them as he may, the culture and values Twain is supposedly taking a stand against here nevertheless laid down the foundations of the ones he wants to glorify. (He only acknowledges slavery as sourcing from Middle Ages and Catholic Church (completely ignoring various ancient civilisations that practiced it), but little else). Said elephant is even further bloated by several comparisons of "ignorant people" of Dark Ages to several Native American tribes. (Aptly, Hank does embody the trope of "Mighty Whitey", even without racial differences.) Yes, he even fails to be consistent in his allegories and basic statements.
He shifts from straight satire to outrageous hyperboles, such as the episode where everyone but our "hero" believes that a bunch of sows are noble ladies. Again, nothing wrong with that - if the whole work was like that. Magical reality is switched on and off as it suits the purpose.
Yes, this form - the satirist rambling about a subject without much thought for story as a story, only to get the point across - exists and is a valid expression. But there is a good reason why few of them stand the test of the time and I doubt Yankee would have either if Twain hadn't written other, much better works.