The most perfect monetary system humans have yet created was the world gold standard system of the late 19th century, roughly 1870-1914. We don’t have to hypothesize too much about what a new world gold standard system could look like. We can just look at what has already been done.
Contrary to popular belief, people generally did not conduct commerce with gold coins. Yes, gold coins existed, but people mostly used paper banknotes and bank transfers, just as they do today. In 1910, gold coins comprised $591 million out of total currency (base money) of $3,149 million in the United States, or 18.7%. These gold coins were probably not used actively, and served more as a savings device, in a coffee can for example.
Silver coins were also used, but by then they had become token coins, just like our token coins today. By 1910, most countries in the world officially had “monometallic” monetary systems, with gold alone as the standard of currency value. This eliminated many of the difficulties of bimetallic systems, which had caused minor but chronic problems in the earlier 19th century