The game never really gives a conclusive answer... either that or I missed it. Even Dagoth Ur asked you is you really are the Nevarine. Also, there were like 8 failed incarnates, so how could they all share the same soul?

According to prophecy, only Nerevar incarnate can wear the Ring of Moon-and-Star (the Dwemer ring of Nerevar himself, blessed by Azura - all others are killed). Azura, Vivec and Almalexia seem to think you are, although in the end it's up to you how much you embrace it, as you say you can tell Dagoth Ur that you haven't a damn clue.

You have the choice to completely deny it; it's YOU who decides if you're the Nerevarine or not.

I kinda read it as yes you were. But in a CHIM-ish sort of "We is all I" way. Everybody is reincarnated from the same spirit energy out of the dreamsleeves so technically every one who was born after Nerevar died is his reincarnation. But the prophecy was speaking more figuratively. A spiritual successor (pun) who could reunite Morrowind against a common foe. Like he did against the Nords. The failed incarnates where people who matched the prophecy but failed the saving throw. Just bad luck.

You survived the Corprus, didn't you?

His spirit has come back before; check the failed incarnates. That's really Nerevar's spirit. Remember that myths are real in TES; that's actually his spirit.

And CHIM doesn't work like that. At the risk of starting an "oh-so-fun" CHIM debate, CHIM is realizing the world is a part of YOU, NOT the other way around; you still retain your individuality after discovering "God and your place in it." CHIM is selfish as [censored].

Maybe Jiub was the real Nerevarine and they chose you to come with them by mistake, he does become Saint Jiub after all. As for surviving corpus, a wise man once said "Just lucky i guess!"

Another wise man once said "In my experience there's no such thing as luck."

Touche, but tell that to my dunmer with level 100 luck stat

Fair enough. But you can talk to the failed incarnates. How can you talk to Neravar's soul if your using it. He some how has to have more then one spirit. Which is why I take a less traditional interpretation of "reincarnate" If Azura was just bringing back Neravar why not pull a Umaril? Some how the Nerevarine Prophesy fits her sphere better. But each incarnate is a different person.

Well, then you're just saying "f*you" to the universe, accompanied by a rude hand gesture as you plummet off a cliff for fun.

Well, reincarnation wouldn't really work unless the souls could divide or something- like a metaphysical mitosis kinda deal- on account of the fact that babies are born all the time, and the population keeps growing. I doubt Nirn has the exact same population it did 1,000 years ago.

So if the failed Incarnates truly are Nerevar reborn, then yeah, you're talking to yourself in that cave, and it makes perfect sense. Assuming reincarnation and ghosts and goddesses getting revenge on magical elves who used the heart of a dead god to become gods themselves makes sense, of course.

An what would the problem in that be

I'm pretty sure Azura wrote the prophesies herself, and came up with the whole idea of the Nerevarine, so that she'd have a bunch of toys to move around.

There's pretty strong evidence the player-character is literally the reincarnation of Lord Indoril Nerevar. Whether Azura had a hand in arranging this is uncertain.... but you do wield One Ring Under Moon And Star, and that ring only ever chooses one person to wear it.