Need help fleshing out a world

[MossyMeow]

I'm planning a campaign set in a homebrew world that has been a bit of a pet project for me these past few years. The best way to describe my creative approach is "pseudo-historical"; basically, I'm attempting to make a semi-realistic world by looking at a fantasy setting through a historical lens. Of course, doing this means twice as much work, since I can't (or more accurately, won't) just say "this is the way things are." I have to explain why this particular country has X form of government or follows X religion, even more so than a normal campaign setting. As a long-time lurker, I know this forum has some great creative minds who could help me iron out some of the kinks.

The campaign itself is set in a generic desert area that's half Egypt, half Arabia, plus a little bit of random unrelated lore thrown in for good measure; I dislike settings are just real world cultures, but with dragons. The main city in this setting, Jubail, is loosely based on pre-Islamic Mecca: a sort of pilgrimage site for all religions. Unlike a standard D&D setting, this world has no definite proof of the gods' existence, much like our own world, so religion is much more varied.

The reason behind the Egypt-Arabia mashup is two now-defunct empires: Aboukir, which is the vaguely Egyptian half and fell thousands of years ago, and Al-Khutt, which is the slightly more Arabian, although it still has a strong pseudo-Egyptian flavor, since it was actually a splinter group that gained power after a civil war caused by an uprising of a dragonborn prophet who stirred his enslaved people into action. I also decided that the ancient elven empire, called Sharazur, fell due to part to the mechanisms of the first king of Al-Khutt, who pitted them against the orc kingdom, Tabrizar. Both kingdoms fell thousands of years ago, while Al-Khutt fell only recently. Both the orcs and elves are now nomadic; the elves are referred to as the Lashadur people (or, both incorrectly and offensively, Lashadurs), after the name of the captial of Sharazur, Lashadea.

Okay, information dump over. I have a lot more random thoughts and ideas in my mind, as well as the names of the other places like the kingdom of the dwarves and halflings, but I'm not entirely happy with them, and I don't want to make this post too long. I want to make my setting unique, while still keeping the races and classes familiar.

I need help with connecting the dots of this setting and making it feel alive and real. I'd be happy to answer questions and brainstorm with anyone who'd like to help. Ideas, even crazy ones, are very welcome!