Why is Adam's beer water?

This word comes from the Bible and the Jewish tradition about Eden.

In this tradition, God only allowed Adam to drink from four small rivers in the Garden of Eden, and nothing else was allowed.

Later, people used Adam's ale to laugh at people who only drink water (but can't drink).

Malt wine is fermented from barley malt. This is a kind of beer. But hops are usually not used for production. Beer and ale have always been synonyms. Until modern times, people used to use beer to represent beer.