I'm not all that comfortable with that level of worldbuilding. That involves world-shaping events, not just changing minor details. Which means that my real problem is with the Red Sleep and the Plaguemother. Apart from that, I don't really find the backstory to be a problem. In fact, Khemisi Idir might make a good plot element later. So, if you could remove or alter the part about the Red Sleep and Plaguemother, it'll be fine. :3

EDIT: It also might be better for group interaction if he appears a little more human.