I find it hard to just write off Ramuh as a mere conjured up image of Sylphic prayer. It just doesn't match with the character we've seen in the 2.3 cutscenes. Ramuh remembers a time before the age of man, as if he was there when it happened. You could say that just represents Sylphic desire of a world without man, but why then summon a primal that looks like a very old Elezen? Out of a desire to have man as their protector instead of aggressor? I suppose that could fit, if you squint, but I don't like it myself. I always thought the original primals we face were pre-existing souls, or personalities if you will, that existed on their own in the lifestream. Self-aware and independant beings, but without corporeal form. Kind of like the Elementals. They can manifest in the physical world by devoted prayer and with the aid of crystals, but they're not "made up" by mortals and when slain, their soul and self-identity remains and returns to the Aetherial realm. Then Moggle Mog came along and muddled things up. Then Bahamut and Shiva and Odin made it even more complicated. Then Hraesvelgr and Tiamat threw up even more smoke, and now we have a difference between Eikon and Primal. Seems the longer we go on, the less clear it becomes.