What do we know about sorcery?
1) It uses devices ("talismans").
2) Its terms and commands are garbled English words (yz'raksis nyuyz'r = user access: new user, for example).
3) The World uses a life-support system, which converts poisonous gases into breathable air. This system is a huge sorcerous talisman.
So, it looks quite possible that English-speaking humans created the World with technology, and later the inhabitants learned to manipulate this technology a bit - which is the art of sorcery.As for Ethshar gods being A.I.s, that's just a guess, but I remember the author saying that they have to respond if called upon in the correct way.
That can be confirmed or Jossed by a short story when a theurgist accidently summons a god from another world - namely, Santa Claus from Earth.
