The movie is called Final Destination. It's quite obvious that the Final Destination is Death. You can't escape death. When a character doesn't die or survive a movie, that just happened because it wasn't her/his time to die. The whole thing is obvious. You can't cheat death, because death always comes and nobody lives forever.
The only thing that needs explanation ( imo ) is why the characters have visions and what's the point of these visions. If they're always meant to die, then what's the point other than Death itself toying with them? lol