Pretty much everything is derivative in some way. I think what is unique here is that we get to play an Avatar of a God - infused with the divine essence of the Lord of Murder - yet still also we have our own sense of self and our conscious of our decisions. How that will play out should be an interesting journey.
At least I have not seen this exact take on that.
I don't think we know enough to claim the Dark Urge isn't an origin character, although you are welcome to your opinion and to speculate. You seem to have strong feelings about this.
No one was claiming it was a wholly original concept.
