The whole "we become the Ancient Azem" isn't really possible for us as we see our WoL as the game has repeatedly stated that people can have the same souls but be completely different in every way. Hermes to Amon is the usual example used, but compare your personal WoL to Ardbert, and Emet repeatedly made it clear we weren't HIS Azem.

That said, maybe another shard of Azem is behind the key? It's possible ruins of the Ancient society exists on other shards just like we saw on the First, or. Just maybe, the Ascians tried to raise one up in the past?