Point taken. Here it is again.
"I've seen this wonderful little theory on the Final Fantasy XV Forums via GameFAQs. Unlike most other theories (which seem to degenerate into rants or overlook state facts from Tabata or others), it seems to take what is known about the game from a development/preview standpoint and run with it in a sensible way. And it creates something that is actually quite compelling. As it's just a theory, I guess there's no harm. As it might be a potential spoiler, read at your peril!
https://forum.finalfantasyxv.com/discussion/2565/ffxv-story-theory"
Edit: It doesn't address those machine things in the cover art. That's a notable hole.
Edit 2: That theory above got me looking at
the artwork again (can't embed the image for some reason). I've long suspected that the fish woman on the right is Leviathan. The artwork seems to divide into three layers: the divine beings at the top with the mysterious Goddess at the forefront blessing four humans (and possibly a representation of those machine-like things on either side); the middle level shows five of the six Archeans sitting on clouds watching the scene, and the bottom area is dominated by monsters/Daemons.