And also ells, rods, cubits, paces, furlongs, oxgangs, lots, batmans… all with subtly different regional definitions (with regions sometimes as small as one village).
People used loosely defined measurements based on things like their own body parts or how much land they guessed their ox could plow on an average day. Things like mathematical convenience or precision were not all that important; being able to measure (or estimate) without tools was.
Dust. Dust never changes.