I think the flood and the storm came on the people of prophet Nooh alone. I think it was area specific.
You would be right. When the bible was written they didn't know about australia or the america continent. thus the specie of human inhabiting were not reffered to.
The flood spoken about was one over persia.back then that was the whole world to the those people
if you look at the scale of flooding queensland recently had, it was a massive massive area. probably as big as the world that existed to those who wrote bible back in the day.
After all over 1 thousand years later they still thought the world flat.