What's the point with that quite lackluster story in Endwalker?

[CrownySuccubus]

How does 100% hyur like people evolve into different races (honestly though, it's hard to believe a hyur evolve into, say, lalafell)?

If you think that's difficult, try imagining the Ancients evolving into Sylphs, Ananta, Vanu Vanu and other beast tribes.

Remember, it's been established that the only real difference between beast tribes and the main races is prejudice based on physical beauty. They were kicked out because the "spoken races" considered them aesthetically unattractive or otherwise revolting. Most members of so-called "beast races", if they are raised or socialize with, the regular cityfolk, are basically indistinguishable. So that basically means, they're likely descendants of Ancients as well.

Imagine being an Ancient and waking up one day in a Namazu's body. (Granted, it's unknown if this actually happens. Every Ascian or reincarnated Ascian we've seen thus far have been Hyur, with the one exception being Amon, who was Elezen.)

EDIT: Although, EW also seemed to be hinting that the Allagans may have created some beast tribes. One of their scientists was hysterical about the fact that Amon had given some random test subject the head of an elephant (possible origin of the Matanga).

No, I mean the actual restoration of the world, i.e. the second sacrifice. The person was arguing despite what Hythlodaeus said in ShB (and apparently despite us seeing the world ablaze in the Amaurot dungeon) that the world wasn't beyond salvaging, saying that since we've overcome calamities they could overcome the destruction brought by the Final Days. They were taking the post-Elpis cutscene literally, with the Final Days still occurring in the background, that Venat had stopped them from returning the world to the way it was.

Oh okay. Your confusion makes a lot more sense with that clarification.