Primal confusion - spoilers

[Andres_Lonegrief]

After completing the story quests I'm a bit confused about the primals' origins since what we have learnt so far doesn't really match. I guess I missed a few pieces.

FFXIV (1.0 and 2.0)
We know that during the Silvertear battle in Mor Dona, the Garleans fought against Dragons and that the Midgarsomir destroyed the Agrius (the big airship we can see and raid in Mor Dona) causing a massive aetherical explosion that allowed Primals to roam in Eorzea (still, they need crystals and prayers to acquire a physical form).

We can see this in the 1.0 opening movie (where Titan and Ifrit are first seen).

In 2.0 we just know that the beast tribes love summoning primals to get rid of people or to protect themeselves (the sylphs).

Known primals: Odin, Bahamut, Ifrit, Titan, Garuda, King Mog (more or less), Leviathan, Ramuh, Shiva.

HEAVENSWARD
Here we learn that Primals aren't real gods but an aberration of what the beats tribes think their "gods" are.
This makes sense with King Mog and could be ok with almost every primal except Ramuh: he wants to test the Warrior of Light's strength and isn't really an enemy. How come?

Also, if the Silvertear battle allowed the primals' spirit to roam in the lifestream, this means that the primals have an identity regardless of the beast tribes' representation, which doesn't fit with what we have learntin Heavensward.

Finally, we know that Tiamat learnt to summon Bahamut back when the allagans were a society (so long before Silvertear's events). What "sealed" the primals back then?