Is Sephiroth actually Jenova?

[The Crystal]

stuff

Wow, you're sure of yourself (and frankly, come across as rather arrogant)

True, Sephiroth was controlling Jenova rather than the other way round, and I had some things mixed up, but Sephiroth himself was always sat at the crater. The one you follow around is Jenova, it is indeed Sephiroth controlling 'it' but it's not his body, which was always sat in that crater. He's controlling Jenova's shape shifting abilities to appear as himself.

It's been discussed countless times on here over the course of a decade...

Also if you supposedly destroyed Jenova just before Tifa comes to ask for the black materia, how does that explain there being 2 Sephiroths, one wandering around outside and one sat in his cocoon? How do you explain the thing labelled "Jenova" that you fight in the final battles?

Sorry if I was rude, it wasn't my intention, really.

The body you follow during the first half of FFVII, is Jenova being controled by Sephiroth. The UOG explains that he/she throws parts of his/her body against you, and those parts transform in Jenova-Birth and Jenova-Life. But when the party reach the Crater, Jenova's body itself becomes Jenova-Death. After you kill it, the body Sephiroth was using during the first half of FFVII is gone(Sephiroth at the Crater - "You're right. This is the end of this body’s usefulness").
The Sephiroth/Tifa you saw after that, was nothing more than an illusion(like the Nibelheim created by him in that place). This is why he/she needed RedXIII to give the Black Materia to Cloud. Sephiroth/Tifa couldn't pick the Materia from him, because Tifa/Seph was just an illusion.

Before the final battle you fight Jenova-Synthesis. That's the result of the Reunion. All the cells inside the clones and the remaining cells of Jenova's body(and her head IIRC) came together, forming that body.

naw man, thats all Jenova.

Jenova/Sephiroth said he became a traveler of the Lifestream. He said that he wanted to summon Meteor and become a god by absorbing the Lifestream.
But you are stating it was Jenova speaking, not Sephiroth. So, you are saying that Jenova could speak even brain-dead, and that it was all her plan, not Sephiroth's(contradicting what the creators of FFVII stated)?

And look at that:

Jenova will be at the Reunion. Jenova will join the Reunion becoming a calamity from the skies.

If it's Jenova speaking, why she is talking like Jenova is another person? I will tell you why. Because it's Sephiroth speaking about her, through her own body.