Imperial basically developed by picking a useful measure at each given scale.

For example, a mile was originally 1000 paces, and wasn't standardized at all. The first Roman legion to march down a road would stick mile markers down based on the length of their stride.

A furlong was one agricultural furrow long - the distance you'd plow with your Ox.

A foot was originally someone's literal foot.

It's inconsistent for the same reason a meter doesn't go neatly into a light year. That doesn't make it good, but it's a very human system of units.