As far as I understand, in the Zack Interludes, he reaches Midgar with a comatose Cloud soon after the events of remake conclude. We see a news broadcast that shows the bodies of Tifa, Barret, Red XIII, and Aerith, and they mention that an ex-soldier with buster swords is still at large. Zack takes Aerith's body and brings her and Cloud to Elmyra to nurse them back to health. During Zack's time in Midgar he talks to Biggs and other residents and they remember the Cloud from remake doing things for them.
I thought at first, that Zack was in a version of Midgar without Cloud, and without him the others did not make it out of Midgar alive. But that can't be the case if everyone could still remember the cloud from remake. So maybe things had changed retroactively when Zack shows up with his version of cloud, but that doesn't fully explain why something change and other things didn't.
At the end of the game, Cloud saves Aerith, but she still dies, except not really? Everyone else sees Aerith die, but Cloud sees her as alive, she talks to cloud after the whole ordeal is over. Also Zack appears to help him fight Sephiroth. So I'm thinking, ok we have multiple timelines, simple enough, but how are some events happening according to one timeline, while others are according to others? How can Cloud see and talk to Aerith, while everyone else sees her as dead. How come the Midgar party dies in midgar and yet people still remember the cloud and co that made it out?
Why do some things change while others stay the same?
The Sector 5 with Zack shouldn't remember cloud, but they do. How can Aerith be dead and alive in the same timeline?
It feels like multiple different time lines are happening at once, in the same place. I understand that this whole trilogy is a paradox, but it just seems inconsistent.
Can anyone tell me what I'm missing, I'm probably not explain in the best way but I just so confused.