Took me awhile to get through, of course, but this is a truly impressive piece. Kudos to all of the work that went into it. The flavor is unmistakable, the setting well defined, the plot woven throughout. The setting itself is usable far beyond the included adventure. I especially love the idea of the lush caves hidden beneath the dry desert. If I ever run a desert campaign, I will have to use this.
I don't see how I could give this anything but a 5/5.
While I would certainly run this as an immortal son of a goddess, I would also make full use of the red herrings provided to thoroughly confuse my players. Especially if they had a stake in whatever possible changes might be coming and need to discover if Jaith is merely a messenger or an active participant.
Overall, I think this is an excellent idea. This is an intriguing race, just alien enough to make interacting with them interesting and quirky.
I would also like to see some detail about how the eye color and affinity aspect works. Perhaps some concrete examples?
What sort of advice are you looking for in order to take it out of Advice Requested?