Noah is a Babylonian “deluge myth”. Judaism didn’t even exist until 1,000 years later:
It tells of how Enki, speaking through a reed wall,[v] warns the hero Atra-Hasis (‘extremely wise’) of Enlil’s plan to destroy mankind by flood, telling the hero to dismantle his house (perhaps to provide a construction site) and build a boat to escape
This means that originally the flood was caused by one god and mankind was saved by another. That’s a better explanation than “God was angry but bipolar, so he saved one family and killed everyone else.”