Honestly, damn near every single thing was colluding for Zack surviving. And yet he-barely- did not.
Cloud was almost conscious- he could kill the three troopers. Turks were almost there, with orders to save both of them. Zack was moments away from rolling
which would have saved him. Not to mention that it was 3 low-ammo grunts in the very end. If Zack had a lighter sword, he might have also survived. That one's iffy- smaller sword means he's significantly less exhausted using it, but he can't use it as a shield as much.
There was a couple of other things as well, but I can't remember them.
Also, none of those people you just mentioned were straight up main characters quite like Aerith was. Let's be honest, pre-Aerith's death it was pretty much the story of Aerith and her bodyguards, from Cloud's point of view. And we were already aware Cloud was a biased narrator at that point. It wasn't till her death that the party actually went 'Stop at all costs'-mode.
Cloud was almost conscious- he could kill the three troopers. Turks were almost there, with orders to save both of them. Zack was moments away from rolling
Great Gospel before his reels shattered
There was a couple of other things as well, but I can't remember them.
Also, none of those people you just mentioned were straight up main characters quite like Aerith was. Let's be honest, pre-Aerith's death it was pretty much the story of Aerith and her bodyguards, from Cloud's point of view. And we were already aware Cloud was a biased narrator at that point. It wasn't till her death that the party actually went 'Stop at all costs'-mode.