I've been thinking perhaps we're one step above just being mega tempered lol (eldest primal tempering, != to what we know), so Zodiark has Ascians.. Hydaelyn has the 12? Who perhaps were a core part of producing the sundering (splitting into 12 shards, for the 12, 13 if you count the "source/original").
Our legacy tattoo is awfully Ascian mask looking:
Maybe we're the 13th (+/- x).
Perhaps that Ascians are a bit like primals of primals, or something akin to FFX Tidus - a manifestation by spirits*. Helping explain our immunity to primal tempering, our infinite teleporting (we don't get anima sickness), our time issues (time bubble, how time passes, and does not pass), and our near endless ability to gain strength as we gain more faith from the people around us. Also like Ascians we had that whole "mortal body" concept, like when Leviathan ate the Sahagin (who had echo and transcended their mortal form) and iirc we were told we weren't nom nom-able since we had a body to inhabit. If we're more powerful perhaps we can nom nom weaker primals, or already do when we win... lol (we're told as much with a whole "you have no idea the true power of Echo").
In that sense I think having echo is just more like saying you're a made of, at least in part, of faith and fantasy (primal/primal-like, I don't think primals can temper each other either lol) and your ability to see things is just your tie in with energy (which is all around).
*In another thread of semi-related topic discussed the possible purpose of making one source two (two primals from one entity "but why?"), and pondered that it might be that the Ascians are truly ancients from a long long past civilization that went through the brink (and made a last ditch reboot script). If one is familiar with FFIX and Garlond / Genome, something drawing similar to that. Why it all went wrong being something about the twelve (also ancients) taking a liking to the new life made during the reboot and deciding to stop the whole process but it cost them dearly (locking away Zodiark, because = Zodiac Ark). Also seems nice in that the true form (or at least 1.0 form) of Ascians is a bit undead wraith (remnants).