The agnostic is not just interested in whether there is a way to know we are created or not, but if any God(s) exist.
That is the difference between agnostics and Liminalists.
Limimalists are not interested in addressing the second question until the first question has been answered.
People who don't believe that there is a creator and don't believe we exist within a creation, are not 'theists'.There are a few religions with no deities, and others with God deities that are not creators