did you read what I wrote? I said before Danuser people thought of Elune as a more capital-G God of warcraft, from how she was described and so on.
then I said: BEFORE THIS CINEMATIC, some people theorised she was a first one
obviously, we only learned of the first ones this xpac. And when we did, many people made that jump for Elune based on her past descriptions and such.
no, she's been nerfed cause beings like the Eternal Ones, pantheons or w.e have limitations and such. For example, we know Elune is not omniscient or omnipotent due to her not knowing about what was happening in the SL, and not being able to do anything about it.
the first ones are described or thought of as the beings that maybe literally created the entire warcraft universe itself: the cosmic powers, the shadowlands and all that. So their power is tiers above what the eternal ones, pantheons are.