Just a random thought.

Seeing as what separates the players from the NPC's, in TESO Lorewise, seems to be that they all had their souls taken by Molag Bal, how could that have happened? Did Molag Bal send an influx of whatever people resided in his realm into Tamriel? If so for what purpose? How could he have? If not? How could he steal that many peoples souls? The hooks? Did he yank them from the dreamsleeve and put them in mortal vessels? Can he do that?

From the Doors of Oblivion.
" 'The sky is on fire,' I heard him say as he moved on to the next realm. 'The ground is sludge, but traversable. I see blackened ruins all around me, like a war was fought here in the distant past. The air is freezing. I cast blooms of warmth all around me, but it still feels like daggers of ice stabbing me in all directions.'
This was Coldharbour, where Molag Bal was Prince. It appeared to Zenas as if it were a future Nirn, under the King of [censored], desolate and barren, filled with suffering. I could hear Morian Zenas weep at the images he saw, and shiver at the sight of the Imperial Palace, spattered with blood and excrement".

Doesn't seem like a place where people can live. Any other sources on it?

I am having a hard time imagining how Molag Bal could steal thousands of souls from various people from different races and ideals on Tamriel. This is a topic worthy of discussion I believe. It also needs light shed on it by the devs of TESO but that will not likely happen for some time.

Thoughts?

My understanding is that TESO will have a single-player oriented storyline, so perhaps we can assume that, lore wise, there's only one PC in TESO.

To be fair, the PGE also states that there were plenty of "Would be kings." all making claim for the throne. That in of itself is a valid explanation, to me at least.

Right but that's the explanation for the PVP, not the soul stealing origin thing.

Non-constructive thought: I still do not trust ZOS and the TESO staff to not ruin my beloved elder scrolls lore. Everything I read about it is like a sermon of Molag Bal, it wreaks havok on all my senses and leaves me feeling violated.

Slightly more constructive thought: Maybe it has something to do with the underking.

New information has thistime period also being called something incredibly dull and lame sounding. The Age of Heroes. This implies, that canonically, there actually were indeed many many heroes.

This whole souls being stolen thing sounds stupid to me. I would have preferred there was zero origin related things to our PC provided by the game. Seems stupid to tell everyone that their souls are stolen. Maybe Molag Bal has laid claim to everyone's soul on Tamriel but it seems impossible. However we have nothing to judge the situation by as far as I can tell. When has a Daedric Prince tried to pull Tamriel(maybe even Nirn) into their Plane of Oblivion before? How can Molag Bal be pulling Tamriel into Cold Harbour? Seems like that has dire implications for the entire Aurbis. Feels like a 'i am going to pull Universe A's box from Universe A while Universe 1 does the same with the box from Universe 1' from Futurama moment. In other words, does not compute.

I also have many concerns for TESO to do the lore i knew justice. I feel the same about BGS as well though. They seem to be doing the boring and therefore wrong approach imo. TESO might be doing the interesting but still wrong approach. The only interesting bit being a possible good reasoning for the factions and other new things like the Pretender to the Tribunal thing.