it's only been recently that I fully understood that Jenova had shapeshifted at all.
Tell me about it, I just realised yesterday xD reading through these last posts !
I was under the exact same assumption that it was a telepathic projection from the North Crater, even seeing people talking about shape-shifting, to me it just referred to the projection having Sephiroth's shape, and then yesterday I was all OMG x)
It's funny you said that, that's exactly my boat ^_^
That's an interesting way to look at it. I mean it certainly fits. I was always under the impression that Jenova just wanted to suck up the lifestream and leave the planet as an empty husk, but I don't see why your idea couldn't be true.
Both are compatible. The Planet tries to heal itself from a great injury with a huge amount of Lifestream, Jenova sucks all of it up and after will continue to parasite the Planet till Holy dies, Sephiroth at the center of the wound becomes the almighty soul of the soon-to-be-wasted planet, they are now like the nerve center of the planet and when they need more "food" they decide to move on to propagate Jenova and to parasite another planet.
And I see Sephiroth as an extension of Jenova, he was born as that. Jenova's cells grew up within him as he was growing up, and made what he is and who he is. For me he is like fused with Jenova. Like they both live through each other.
Sephiroth could even be the mind behind Sephiroth-shaped Jenova.