I only have one God as there can only be one God. All else and others falls under Him and His jurisdiction.
There can only be one First Cause. The First Cause could not have been caused else it would be the second cause. So, there can only be one that that One is eternal.
I think you will find that believers in other gods will make the same argument for their gods as you have for yours. In addition, there's no reason to accept your claim that there can only be one God. History proves you wrong as there have been many gods who have served their tenures and eventually retired or were let go. All of those gods as "real" as your gods.
There's no reason why your gods can't be subordinate to and under the jurisdiction of Ganesha, Shiva, Lakshmi, etc.