Enkidu, I know they officially count him as a primal, but for lore discussing them I really don't feel he is relevant. He's the joke summon of a joke character in a storyline that pretty much entirely exists because it's funny

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The ingredient in Primal creation that IMHO is most often not discussed is a soul, it's why a captured Ifrit or Bahamut or whoever is a big deal, the summoners can't just gather crystals and make another.
Ifrit, Titan, etc. are drawn from the lifestream by their followers prayers and given form through aether, Shiva, Pheonix, etc. use their own souls, either on purpose or inadvertently, as the foundation for the primal.
Makes sense to me, and explains why the overworked guy delivering carts of crystals who thinks he really deserves a pay rise isn't accidentally turning his delivery into the fearsome
'Sack of Gil: The Lord of frivolous spending!'