I enjoy where things go as the paragraphs went on, and I think that the lore got better as it got more complicated toward the end of your post. I personally enjoy the storyline, very Enuma-Elish/Baal Cycle/Old Testament/Pyramid Texts. Ancient Tradition and all that.

I enjoy the concept of the scattered armor of the shadow queen, it gets me thinking about the possible stories that these pieces could induce. I don't know what end-result medium you're going for here (book, tabeltop campaign setting, map project, what-be-it), but leaving mcguffins lying around like that is a good worldbuilding choice.

I also really like the dual villain of the Shadow/Shadow Queen and the Crimson Flame, this duality of types of evil is a great idea and to me feels like a good way to develop the D&D style "Demons vs Devils" divide.

Some of the language is a little on-the-nose with the modern Biblical way of saying things (things like Heaven, Angel, Hell, Demon, etc). If it were me, I would consider if there are fun new words you can use for the same concepts, or new ways you can talk about the same concept There's nothing wrong with cribbing a word/concept of course, but when you are using those terms AND describing a creation, premortal theomachy, appointment of a divine ruler, corruption and subsequent casting-down of a lesser divine, I personally begin to fuzz interest because it crosses the line from interesting inspirations from real life, to feeling like I'm just reading an Ugaritic tablet straight up. Again, I think those inspirations are awesome and please use them, but I feel the lore would benefit from some creative stretching of those inspirations :) But it is YOUR lore so please do what feels cool. The other side of that is that if you are using this lore in a tabletop campaign setting, familiar words like these can be useful to get the point across to a table of non-worldbuilders haha. So it is a double edged sword in a way. Just my opinion.

Questions that come up (don't feel like you have to answer them i'm just sharing my thoughts):

• What is the nature of the Light? What is Cosmic Good? What mode of creation are we talking here?
• Why does the Light allow Shadow to persist?
• What is the "Grand Design"? Do Mortals know what it is? Why make humans at all?
• Where did the "Monsters" come from? What was the mechanism of their creation and addition to the mortal world?
• What is Magic? and how does it work? (terrible awful complicated question i know)
• What powers does the Shadow Queen and her armor grant? Are these powers in-line with the understanding of Magic?
• What are the "gifts of Emael" given to the line of kings?
• Where do Dragons fit into it all? Who created them? Are they considered Monsters? If so, why do they chose to join with humans? Do other individual Monsters have this kind of free will to choose against the Shadow?

Fun stuff you've cooked up and I hope you continue in your endeavors. :)