Kel'thuzad was raised as a Lich. Dread Lords never truly die. Saurfang Jr. was undead. Nefarian and Onyxia were an experiment gone wrong, basically falls into the category of undead.
Please name one true resurrection. The Ancients? They are eternals that always come back given the time. Cenarius? Same thing.
Who are you talking about that isn't immortal, has had a resurrection but isn't undead? Am I missing someone?
Yeah, Thrall has had that weird questline in Cataclysm, but did he truly die to begin with? I don't think so.