And why are you ignoring the mako commentary? Because it's there. Sephiroth talks about travelling to the Promised Land with Jenova, because he still thinks she is an Ancient and doesn't know what he finds out while in the Lifestream: Meteor, the Northern Crater, too say nothing of the fact that Cloud and the other Sehiroth clones that Sephiroth uses in FFVII are only created after this by Hojo. You're telling me Sephroth was depending on Hojo's genius?

Zack fails, Cloud stabs him in the back, Sephiroth comes out of the reactor, is all "How dare you", Cloud tries to fight, fails, Sephiroth tries to finish him off and Cloud proves to suddenly be too much too handle, Sephiroth looks in his eyes, sees them glowing and then hauls ass to get himself into the Lifestream. In fact, the scene is even wierder then in FFVII, Cloud regains conciousness, he grabs the supersharp sword, pushes it down so he's on the ground again, he then pushes himself further up the sword, then he's randomly ejected two feet away then Sephiroth is like kthxbye.

Our great villian ladies and gentlemen.

We KNOW Sephiroth did not have FFVII planned out back then, Last Order doesn't change this. As for Cloud being badass, I don't know his rank. He's sixteen and between Before Crisis and Crisis Core we see him be the only grunt to survive half a dozen dangerous missions.