GOD, perhaps. Gifted Original Developers. Seriously though, if the simulations was of such high fidelity we would probably be unable to tell, barring things like the cat glitch in the matrix, that we were ever in a simulation. If the simulated actors had a similar level complexity to ourselves can they be considered alive and sentient. Do they have rights? A few SF stories have covered the morality of turning off such a world and killing billions of simulated beings. Religions often have the 'world as illusion memes' (gnostic Christianity, Sufism in Islam, just about all of Buddhism), perhaps the great Bard said it best.His view is basically that we're going to be capable of creating such a simulation ourselves in future, so it's possible that we're living in one created by someone else. Maybe he's right, but at some point there must be an original non-simulation civilisation
"All the world’s a stage,
And all the men and women merely players;
They have their exits and their entrances,
And one man in his time plays many parts"