Lorkhans status depends on culture.
Example:
But not just in the myths of crazy snake folk, he's up and walking in http://www.imperial-library.info/content/oblivion-five-songs-king-wulfharth. Then the story continues on into the http://www.imperial-library.info/content/morrowind-arcturian-heresy which suggests that dead Lorkhan even ended up advising the next Emperor.
Dead man walking indeed.
Moving on to Tiber as Lorkhan.
As you'll have read in the Arcturian Heresy, Tiber and Ysmir (being Lorkhan) become closely associated, infact it is suggested they both pretend to be the same person at different times. Specifically: "Ysmir, mindful that it might seem as if Tiber Septim is in two places at once, works behind the scenes."
So we end up with this:
Ysmir (Dragon of the North): The Nordic aspect of Talos. He withstood the power of the Greybeards' voices long enough to hear their prophecy. Later, many Nords could not look on him without seeing a dragon.
Tiber Septim (Talos, the Dragonborn): Heir to the Seat of Sundered Kings, Tiber Septim is the most important hero-god of Mankind. He conquered all of Tamriel and ushered in the Third Era (and the Third Empire). Also called Ysmir, 'Dragon of the North'. - http://www.imperial-library.info/content/morrowind-varieties-faith-empire
Two persons, one god. A two-headed god, one of them a dragon. Kinda like that statue of him in Oblivion. But for good measure we might as well throw in the Sermons.
Coincidently this god (one half Lorkhan) takes the place of Shezarr, the http://www.imperial-library.info/content/shezarr-and-eight-divines (http://www.imperial-library.info/content/oblivion-shezarr-and-divines) of Shor.
The obscure texts put a name to this whole party, mantling. Which makes it easier to talk about and it's less work to derive it that way. Do pay attention.