The original Fahrenheit system was actually pretty clever. It set 0° at the temperature of brine and 96° at internal body temperature. That made marking a thermometer really easy. Like, ridiculously easy. 96 is divisible by two many times before reaching a decimal.

Because the freezing temperature of water was really close to 32°, the later Fahrenheit system set that as the lower temperature and 212° as the boiling point instead of using body temperature. That made marking a thermometer more difficult, and basically took away Fahrenheit’s only advantage. It was more consistent though. Now Fahrenheit is formally defined based on Kelvin.

Centigrade was originally marked as 100° at the freezing temperature, going down as temperature increases to 0° at the boiling temperature. Obviously that didn’t last long. The downside is that marking a Celsius thermometer depended on atmospheric pressure. Now Celsius is defined based on Kelvin by -273.15° being absolute zero and a degree corresponding to a very specific amount of heat energy increase.

So yeah, Fahrenheit hasn’t made any sense for many many years.