Question

Let us assume we accept that there is a first existent, and also the claim that a highly complex thing was most likely created by an intelligent designer. If we accept that there is an intelligent designer who created the world, then he himself is an entity even more complex than the world, and therefore it is likely that there is an intelligent designer who created him as well. I understand that one could argue that even if there is such a chain, we have already accepted the claim that there is a first existent, and the being at the end of that chain is God.
But in any case, if there is a God and He is the first existent, then we have accepted the claim that there exists in the world a very complex being (God), more complex even than our world, whom no one created, but who always existed. And if so, then necessarily there is a complex being that no one created, and it is the first existent. Why assume that this being is God and not the world itself? After all, the world is less complex; it is easier to assume that it existed on its own than to assume that God, who is a more complex being, is the one who existed on his own.