Right, but this is why the concept of “plot armor” doesn’t make sense in a coherent story. You’re telling the story of a person, and if they die the story of that person is now over. Introducing a new main character in the middle of the story makes it a different story. If Harry Potter gets killed in the middle of book 4, then it’s not the Harry Potter series, it’s a different story.
A story should be about the most interesting events in a person’s life, because if they aren’t you should stop telling the current story and switch to the other more interesting story. This doesn’t mean the most action packed, a story about a retired former hero might be more interesting than a story about his cookie-cutter heroics in his prime.
Where the concept makes sense is in serialized fiction, especially when it isn’t produced by a single author’s vision. Why does the Joker always escape from Arkham Asylum? Because Batman has to fight the Joker and then Batman has to defeat the Joker. If Batman fought the Joker and put him in prison permanently or killed him then the stories of Batman fighting the Joker are over. And so the Joker has to escape, or turn out to have miraculously escaped the explosion. That’s plot armor. You can’t really defeat the Joker, because there’s always another issue next month and Batman has to fight somebody.
The only time you can permanently defeat the Joker is in a stand-alone work. So Nolan’s Batman or Burton’s Batman can permanently defeat the Joker. But a reboot will happen soon enough with a new Joker and a new Batman.
For something like Game of Thrones, we have several PoV characters. Yeah, Ned Stark got himself killed. But that wasn’t because the author didn’t believe in plot armor, it was because Martin decided that Ned should die because it made the story better. If the showrunners are going to kill off some fan favorite character next episode, what is the point of that? Why was that character a PoV character in the book/show?
This is the difference between history and fiction. In fiction you tell the story you want to tell. If the story you want to tell is about a Chosen One kid who finds the magic Macguffin and confronts the Big Bad and but gets himself killed instead of winning, that’s a fine story. But that’s not because the Chosen One kid didn’t have plot armor, it’s because you chose to subvert the Chosen One trope.
But what would really subvert the trope is to simply not invoke it in the first place. If you hate Chosen Ones then tell the story about a group of nobodies who made a difference not because they were destined to win, but just because they did. Make the story about how individual people live and die but movements live on. But again, plot armor has nothing to do with it.