Assembly lines leverage standardized parts to break auto assembly into discrete components, each that can be done by a small number of people (often just one). Standardized parts evolved into standardized jobs.
Ransom Olds, inspired by a musket factory that used standardized parts with workers each focused on one part, created the first auto assembly line. Olds, the founder of Oldsmobile, did well. His cars sold for $150 less than Ford’s (pre-Model T). However, investors, determined to build pricier cars, pushed him out of his company.
The “disassembly” lines at Chicago slaughterhouses served as inspiration for Ford employee William Klann. One person repeatedly performs an individual task, butchering animals in stations. However, the single station factory is an old concept, arguably dating back to at least Arkwright-era factories.
Ford, via Klann, adopted the auto assembly line. He is generally (and wrongly) credited with the innovation of the auto assembly line.