The "one company for one's whole life" era lasted... significantly less than an average human lifetime. It certainly wasn't present during the Great Depression. It began in the 1950s and ended in the '80s, but even then, people were more mobile than was often said. The difference is that the ideal was to have a long, monotonically increasing career at one company-- it didn't always happen that way-- and that a person who shifted was implicitly assumed not to be successful. A major change the '80s brought about was a recognition that most people's involuntary job changes were through no fault of their own.
Well-to-do 18th-century people prized generalism and aspired to be polymaths. The professions emerged in the 19th century, but these were structured as lifelong careers, not jobs, run by individuals who would develop reputations. Corporate paternalism didn't emerge until the World War I era, when workers moved into company towns, and more services (e.g. medical care) were provided, directly or indirectly, by the employer than the community.
Well-to-do 18th-century people prized generalism and aspired to be polymaths. The professions emerged in the 19th century, but these were structured as lifelong careers, not jobs, run by individuals who would develop reputations. Corporate paternalism didn't emerge until the World War I era, when workers moved into company towns, and more services (e.g. medical care) were provided, directly or indirectly, by the employer than the community.