I'm gonna disagree on Sephiroth being a product of the planet. He's a product of the arrogance of man.

He was conceived when Shinra and Hojo discovered Jenova and put her cells in a human fetus to make a god.

By all measures, he has the powers of a god, but he's ultimately an ego project put forward by an electric company who wanted to drain the essence of heaven for personal profit.

Defeating Sephiroth is telling him he's not prefect or a god and that he too will return to the planet when he dies.

He's a supersoldier made by a capitalist empire and he believes he's better than humanity because he was born powerful. He's like the worst kind of nepo baby who thinks the world should not go on without him.

When he finds out about his heritage, and that he wasn't naturally just born better, he snaps and doubles down on his insistence that he's a god. He goes on a killing spree.

His whole plan is to become undeniably powerful so he doesn't have to think of the material conditions that created him.

Edit - with Jenova being from space, I don't see Sephiroth as being as much a product of earth's wrath. His attempt to destroy Gaia to gain power feels like the ultimate goal of Shinra. He's a a product of Shinra.

Also, I think it would be interesting to see an evil Cetra, but I don't want that to happen in the already complicated VII universe.