Aurax and Aurang are world-born?
For the purpose of our discussion about Kellhus's intellectual ability they are, in my opinion, on the same level as the world-born, so I roughly lumped them in the same category. I also, obviously, make a rough statement when I collate all world-born with the ones Kellhus interacts with. But since those are many different people (from Achamian to Cnaiur to Esmenet) representing many social statures and depths of intellect and education, I feel that it's 99,9% certain that if Kellhus outshines them, he outshines all the other world-born. And also my narrative spider-sense isn't tingling for that 0,01% outlier, I think it's Bakker's intent to show that Kellhus is superior to all world-born.
The only difference is Kellhus grew up secluded, that's why he uses the phrase world born. They are still men.
This is another point on which I disagree. I feel that the Dunyain's intellectual abilities (in general, and not only in Kellhus's case) are so far superior to those of the world-born that the Dunyain should be put in a separate category when intellect is discussed. This is evidenced by their different brain structure (Koringhus references it in TGO when he compares it to that of Sranc), intellects of Kellhus's children and Maithanet, and the fact that the Mutilated were able to subsume the Consult, which consisted of the brightest and most knowledgeable minds of three races.
With the right womb, produce human babies.
Doesn't it seem strange to you that Men generally don't need their wives to have "the right womb" and the Dunyain do?
Also I can't readily agree on the humanity of those babies. Though this shouldn't be taken as disagreement, too.
And, Baller has made it clear that Moe, Kellhus and the Survivor are heads above the rest of the Dunyain.
You see, I don't remember it like this at all. My understanding of his words is, they are "stronger" than the other Dunyain (it's more clear with Kellhus and less clear with his father and the Survivor, the way I recall it), but I don't interpret this "stronger" the way you do. It's like in real life between professionals in a given field, the difference, when it can be calculated, is 1-2% or even fractions of a percent, and it's negligible to any outsider, whose results would fall many times shorter.
This is why I don't see myself being wrong. We differ in our understanding of terminology and reading of the text. It's actually very curious to me, haven't you seen the possibility of such form of disagreement from the start?
[EDIT] But all of this, in retrospect, makes me understand better why you propose that Kellhus could have outmatched the Dunsult by himself. You see the Anasurimbor line and him specifically as very special, while I attribute almost all of his strengths (being arbitrary, 95-97%) to his Dunyain heritage and training.