Future Primals and potential implementation into lore.

[Seraphor]

Of which they are that entity in name only. The ravana and susano-o (not even the same name) from their respective games are completely different, as much as Shiva is completely different from the Hindu god, and bahamut isn't a planet sized turtle

Not really.
Ravana was a four-armed statue that wielded swords...
Susano-o has been a water-elemental, sword wielding summon...


Pretty much the same things.
At least as much as Bismarck was always a water elemental summon.
Garuda was a lightning elemental enemy with a birds head.
Ifrit was always more mammalian than reptilian.

They're the same things as far as the FF series is concerned.