[Speculation Discussion] Our Primal

[Catapult]

The idea of Siren... it's just too mundane. There is already too much lore about the "sirens" running around for it to be the answer here, especially since all of that lore revolves around Limsa.

"The paragon warned me of the godless blessed."
If the "primal" Siren was indeed messing with us, the we would not be the godless blessed.

I'm going to propose an alternate theory: The Lodestone.
The crystal, heart and source of the aether, has woken us to protect her. Just like in many of the earlier FF games, notably III and V.

The second ARR trailer (the one made for fans, not the hollywood one) tells us to "heed the crystal's call."

EDIT: Dropping this screencap here.