Is the Flood a Global Flood?

Every single father, without exception, including origin and augustine, held it was literal. Saint peter says that in the end times, there will be some who deny that hrist will return because all things have continued as they were from the beginning of creation. If this isn't a global flood, what more could moses have possibly added to clarify it was global? And why does noah need to save two of each animal if the other animals can move in?