One plot device from the very first Final Fantasy that I loved was the Time Loop. For those who haven’t played it (major spoilers ahead) the Warriors of Light were stuck in a loop of infinitely fighting the villain who channeled the power of the Four Fiends to be sent back in time 2000 years every time he was about to be defeated. This kept him in power for eternity, until the Warriors of Light discover the Time Loop and learn how to circumvent it.
A major component of the XIV plot is the idea of Astral and Umbral eras. Each era pair is a cycle of rebirth and then calamity.
At the moment we know that in the background of all this is Hydaelyn who guides our hand as the Warrior of Light, and then there is her arch nemesis Zodiark who guides the hands of the Ascians.
My theory is that the Ascians are the “Scions of Seventh Dawn” from the previous era. Elidibus in his grand white robes is the previous Warrior of Light. This group attempted to do what you, Minfillia, and the rest are on your way to do: be guided by Hydaelyn’s Echo for some vague “save the realm” goal.
Knowing that this cycle “from Astral to Umbral” and back again has gone on for a number of eras, I wonder if this is like the Time Loop from the very first Final Fantasy. Hydaelyn recruits individuals who she feels can defeat Zodiark, and gives the power of the Echo to the Warrior of Light of that generation. They go off to defeat Zodiark, who somehow influences the Calamity of that era and causes the Warrior of Light and his team to lose their existence such that they become Ascians. Each calamity is a way of making sure that Zodiark does not get defeated. Something in summoning the Primals may help keep Zodiark in a state outside of our existence (and gives some context to the Sahagin leader scenes with Leviathan where he is possessed by Ascian energies)
We have already seen this begin to occur when Thancred was possessed by Lahabrea.
This would explain why no one remembered the Warrior of Light from before Dalamud crashed. There is a grand amnesia that occurs when the human essence of the Warrior and his team turn into the otherworldly Ascians. Indeed, the plot to the original Final Fantasy states that the Warriors of Light were forgotten once the time loop was broken at last.
The twist here is that Midgardsormr stripped the Warrior of Light of his Echo! This is the loophole, just as the original Warriors of Light in the first Final Fantasy discovered how to break out of their time loop. Without the Echo, we are free from Hydaelyn’s and Zodiark’s pull and cannot become Ascians ourselves.
My thought is that they are two gods using us as playing pieces in a war. Hydaelyn tries to use us to defeat Zodiark, and Zodiark in response causes a calamity and then turns us into Ascians. Then the cycle begins anew.
Not being a loremaster myself, I am wondering if there is evidence to this theory? Just something fun to conjecture about!