I'm still uncertain about the whole business with Wulfharth, Zurin Arctus, Tiber Septim, and the Mantella, but I gather that understanding that is considered key to understanding the nature of Talos. And the general assumption has been, Wulfharth was a Shezarrine, and possibly all three were Shezarrines. Which, by itself, suggests an issue.
That is, I think it's a mistake to assume that an incarnation of a god has the same identity as the god; the connection seems to be more subtle than that. Even if Talos was originally a Shezarrine, or some sort of merging of more than one Shezarrine, Talos is not simply the same entity as Lorkhan; nor is he some lesser version of Lorkhan who has the same personality.
I do not think we can blithely assume that Lorkhan is a benevolent deity, or even that Lorkhan has a consistent purpose over time. Adventurous Willie has a theory that Lorkhan's battle to recover his heart from Red Mountain was a sermon on love. Haute Quêteure posited in a thread recently that it was Lorkhan who tore his own heart from his chest, in a fit of madness. I think that latter theory makes sense, and what Lorkhan's efforts at Red Mountain shows is that he cannot commit to a purpose. Pelinal Whitestrake, a Shezarrine, has something of this aspect of Lorkhan: Pelinal was a champion of oppressed humanity, a psychotic killer, and a terrifying monster who would unmake parts of the world.
Whatever else Talos is, I think he just is enough of Lorkhan to be able to occupy Lorkhan's throne, preventing Lorkhan himself from ever reclaiming it; but Talos himself emulates the Aedra, and acts as something of an Earthbone, empowering the Empire and stabilizing Nirn enough for the survival of the fragile concept of progress.