the word "world" for ancient people meant entire place where they lived.
places that were beyond were often described as inhabited by evil spirits so most didn't dare to go beyond.
nobody was aware of the entire earth or how big the world is.
therefore that flood is more likely to apply for the ancient meaning of the "world"
Every culture who lived near water had a flood myth in their religion. Noah, like the rest of Genesis is taken from Mesopotamian stories.
Noah - Also he sent forth a dove from him, to see if the waters were abated from off the face of the ground; But the dove found no rest for the sole of her foot, and she returned
Gilamesh - When the seventh day dawned I loosed a dove and let her go. She flew away, but finding no resting- place she returned.
Noah - And the ark rested in the seventh month, on the seventeenth day of the month, upon the mountains of Ararat. And the waters decreased continually until the tenth month: in the tenth month, on the first day of the month, were the tops of the mountains seen.
Gilamesh - When the seventh day dawned the storm from the south subsided, the sea grew calm, the flood was stilled;
Noah - And Noah builded an altar unto the LORD; and took of every clean beast, and of every clean fowl, and offered burnt offerings on the altar. And the LORD smelled a sweet savour; and the LORD said in his heart, I will not again curse the ground any more for man's sake;
Gimamesh - , I made a sacrifice and poured out a libation on the mountain top. Seven and again seven cauldrons I set up on their stands, I heaped up wood and cane and cedar and myrtle. When the gods smelled the sweet savour, they gathered like flies over the sacrifice.
Noah - The earth also was corrupt before God, and the earth was filled with violence.
And God looked upon the earth, and, behold, it was corrupt; for all flesh had corrupted his way upon the earth. And God said unto Noah, The end of all flesh is come before me; for the earth is filled with violence through them; and, behold, I will destroy them with the earth.
Gimamesh - “Wisest of gods, hero Enlil, how could you so senselessly bring down the flood? Lay upon the sinner his sin, Lay upon the transgressor his transgression, Punish him a little when he breaks loose, Do not drive him too hard or he perishes; Would that a lion had ravaged mankind Rather than the flood, Would that a wolf had ravaged mankind Rather than the flood, Would that famine had wasted the world Rather than the flood, Would that pestilence had wasted mankind Rather than the flood
Gilamesh - ‘For six days and six nights the winds blew, torrent and tempest and flood overwhelmed the world, tempest and flood raged together like warring hosts. When the seventh day dawned the storm from the south subsided, the sea grew calm, the flood was stilled;
Noah - And it came to pass after seven days, that the waters of the flood were upon the earth.
Noah - And all the days of Noah were nine hundred and fifty years: and he died.
Gilamesh - Gilgamesh, the son of Ninsun, lies in the tomb.