I don't know if anyone share with me this theory, I think the primal Shinryu is based on Azdaja, and recent event in 6.1 and .2 confirm it.
Azdaja breached the void gate the stop the invasion of voidsent aid by allagan, and stopped partially the allagan conquest by consequence.
What if the far east people during that era witnessed the event and believed that a God dragon capable of worlds travel saved all, it is literally what shinryu does and simulates, travel inside of interdimensional rift.
And the single appearance of Azdaja in game actually looks more like Shinryu ( Divine dragon ).
Your thoughts?