So, we ended up with a foot being, well, the length of a foot,
It made sense at the time, and worked well enough.
The history of temperature units is interesting and convoluted, but 32 for freezing is based on binary divisions (64 units) between that and human body temperature (96).
Fahrenheit is quite useful when you are thinking in terms of human comfort and safety.
Summer weight clothing will be appropriate and comfortable at 75, autumn weight at 50, winter weight at 25.