They believe that their ancestors created the earth. Why many should then be blind devout xtians I do not know.
Any thinking Christian (yes, I realize that some may find the term oxymoronic) who believes in the creation myth as captured in Genesis, isn’t really thinking at all. Once a believer has been relieved of the burden of having to accept fables, legends and allegories as fact, it becomes much less difficult to follow the trail of evidence as revealed in the sciences of paleontology, geology, embryology, biology, genetics, anthropology, archeology, cosmology, etc. to the conclusion that the Earth is much older than any religion, and that there is zero evidence anywhere of supernatural intervention.
Almost every god myth states that their god created the earth for them.
@glennlab I have a suspicion that aboriginal ancestors are not gods.