As far as I can tell, Unbreakable was written by taking the plot of The Sixth Sense and search/replacing the text to make Bruce Willis be the kid who sees dead people. Let me show you.
Start of movie: There's something different about Bruce/Kid who sees dead people. The audience isn't supposed to know what it is, but since they have seen the previews, they do. Bruce is unbreakable, the kid who sees dead people can see dead people. Lots of people whisper. Scenes move slowly. Audience wonders when we're gonna get to the part where Bruce finds out he's unbreakable/the kid can see dead people.
About halfway through movie: There is a big breakthrough where the audience "finds out" the big plot point that was in the trailer. More people whisper.
"I see dead people."
"God dammit, I KNOW you see dead people! Get on with it!"
"I'm unbreakable."
"I KNOW you're unbreakable. I want to know WHY!"
End of movie: The amazing plot twist. I don't want to come off like I'm dumping on The Sixth Sense. I really did think it was a GREAT movie, and it had a kick-ass, Twilight Zone style plot twist ending.
Unbreakable, however, did not.
As opposed to the "Guess what, you're a dead guy" showstopper conclusion of The Sixth Sense, at the end of Unbreakable, we find out that Mr. Breakable, in an effort to find Mr. Unbreakable, caused several major disasters and killed hundreds of Pennsylvanians.
What the hell, Samuel L? In your terrorist quest to find this "super hero" that you theorize exists, did it ever occur to you that there are like six billion people on Earth? Maybe killing Philadelphian commuters alone isn't gonna weed him out? Then again, it did, so what do I know about being a supervillain...
Oh yeah, I know that supervillains are intent on world domination. That's pretty much day one, class one of supervillain school. Mr. Glass is the first criminal mastermind that I've ever heard of who's sole evil mission is to search out the super hero who will stop him. He should team up with The Riddler. That way Samuel can find the super heroes, and then Riddler can tell said heroes exactly where and when they're going to strike.
Anyway, here's that four line synopsis I promised you.
1. There's a big train wreck, and Bruce Willis doesn't die in it because he's unbreakable.
2. Despite Samuel L. Jackson's pleas, Bruce Willis refuses to believe he's unbreakable.
3. Finally, Bruce Willis thwarts a crime, because he finally believes that he's unbreakable.
4. It turns out that Samuel L. Jackson actually caused the train wreck in an effort to find somebody who was unbreakable.
Pad each step with about thirty minutes of slow slow action and whispered dialogue, and there's your Unbreakable.
Don't fret, M. Knight Stalagmite. I hear Animotion is looking for a new drummer...