I basically thought about this connection. It's a connection that makes most sense and maybe points to some real world inspiration for Lorkhan's character.

What do you think?

I don't see any similarities.... If I were you I would eleborate...

Both are called monsters in some ocassions (see "Sithis" and the Demiurge being called a misformation), both are the so called "Gods of Humankind" and both trapped inmortal spirits in worlds of flesh created by them that limits their power and their return to Pleroma/Aetherius. I think you were looking at the Demiurge's wrong side (that of a lawful god that longs for worshippers, destroys his enemies and wants order in his "Imperfect Creation") which is represented by Akatosh, who is the same being as Lorkhan. Both are also born form divine entities: Padomay/Sophia

In the eyes of Mer, yes. To Men, Lorkhan is the one who saves them from 'it.'

Now that you say it, maybe Mer=Gnostics and Men=JudeoChristian people. Note that I'm not saying that I agree with the Thalmor, mind you

There is quite a lot of Nostic Christian inspiration to Elder Scrolls mythology, especially regarding elvish mythology. So yeah, to the Altmer and Bosmer, Lorkhan is very much the Demiurge. The material world is also a prison, and there is an exclusiveness as to who has divine ancestry (elvenkind) and who does not (mankind). There is even an Aetherius of sorts, if I recall correctly.

Pleroma, the realm of the Unknowable God, to which the spirts of manking truly belong

TES religion and mythology is a mash up of different real world religions. I think the Christian themes were stronger early on and have been largely phased out and replaced with more of a combination Greek/Anceint Eastern inspiration. There is also quite a bit that is unique, in my opinion.

I think you've found a great connection. Like the Demiurge, Lorkhan is the one who maintains the physical universe. And like the Demiurge, people disagree about whether Lorkhan should also be credited with creation.

The Gnostic/Altmer and Christian/Imperial connections are good ones as well. Altmer, like Gnostics, consider the physical universe to be evil and the non-physical (spiritual/aetherial) universe to be good. Imperials, like Christians, see the physical universe as a necessary step to move beyond to a better existence. The Imperial belief of Aetherius as Heaven is also very christian. If you look at the Temple of the One, I think the connections are even stronger.