To me it seems like most people in this thread simply aren't familiar with Judaism or Islam, because Adraste has parts of all the prophets. Moses, Jesus and Muhammad.
Moses freed "The People", referring to Israelites. Also went to a mountain for a few days to chill out. The Dalish, which she freed, are called "The People" in DA.
Jesus was crucified by Romans and if Tevinter isn't The Roman empire then I don't know what is. She was also given a merficul death, and also betrayed to the Tevinter.
Muhammad was a warlord, same as Andraste.
Maybe it's just me, but it seems pretty obvious that she has parts of all of them woven into her story.
I have a theory regarding the other religions as well. Most of the Elven stuff was revealed in Trespasser, but I personally guessed most of it anyhoot. Flemeth being an Elven god (not using a capital g is intended) was obvious already in DA2 and Solas knew way too much about way too many things. I also think that the Black City is indeed Arlathan, if only for the winding spires that are visible, which is what Solas said Arlathan had.
The whole Titan thing seems pretty clear as well. Mythal faught the titans, this is revelead but I think the origin of the Blight is connected to this. Maybe a spell of somekind caused one of the Titans to become "sick" and that's how the Blight got started, spread through the veins of said Titan in the form of Red Lyrium. It's possible that the Tevinter old gods are actually Mythals generals who were infected in the battle and were then sealed away to try and prevent the spreading of Blight, This would explain why she wanted to get the souls after the Archdemons are killed off and yes, Andraste probably had one placed in her, she's too similar to Morrigans kid with the crazy insights and whispers. This would explain why she can control him and make him come to her, because the original generals/servants had a dip in the well like you/Morrigan had.
The Dwarves were probably shaped out of stone, then infused with Lyrium in some fashion, remember that Red Lyrium can animate objects, as a defense mechanism by the Titans. Maybe to prevent blighted Humans from digging up the Dragons because that's what they do. The Darkspawn are always pushing in the deeproads and the Dwarves are always fighting them, endlessly. The Anvil of the Void is obviously infused with Lyrium and maybe Caridan didn't make it, maybe he found it and such things were made to make Dwarves at some point.
This would also explain why the Tevinter old gods are Dragons, because they are/were servants of Mythal before the Veil and are simply stuck in Dragon form due to being Blighted. Also remember that Mythal can control the Blight. In DA 1 she says her magic can keep the Blight away, probably because it was her doing in the first place, uased as a sort of a biological weapon against a Titan.
This is all pure conjecture however, but it makes sense to me at least.