Where is it written that God cannot, has not, or will not in the future create other species also in His image?
Christians operate on the basis of what has been written in the biblical texts. There is no authoritative source regarding other self-aware, intelligent creatures as the object of creation, but only speculation. The correct iteration would be that God has only revealed Mankind to be the object of His incarnate being, with the balance of creation included as under the domain of both God and Man.
If a creature wants to make it his prerogative to question the Creator and what He has revealed about Himself, he may do so in fine company, with great applause, and with ample self-comfort. But on that account he has no authority other than his own imagination, a creative one at that, since he is created in the image of God.
That is true. I just like being special which is why Satan hates us so much.