Yes we do. Logic. What is the logical conclusion to who created the creator and the creator's creator and on and on?
On the other side of the coin, if the creator simply existed, then I can claim existence simply existed and all that is within existence is natural thus no room for the supernatural.
If you follow any argument to a logical conclusion the end result is very simple.
What we do not know is the infinite possibilities about the nature of existence and that is another topic all its own. But with regards to the creation or the universe or its origin, the answer is very very simple and the answer is a logical conclusion.
One need not be Einstein to understand this.