You lose sight of the time factor.
Manufacturing is and from the late 1700s has been about replacing manual labor with machines. Today this is Automation. Prior to the late 1700's the majority of people were farmers living just barely above a subsistence level. The Industrial Revolution, early on made it possible for a farmer to produce more for the same labor effort. This led to a large throng of former farmers flocking to cities. These are the people who staffed the factories, but, doing that took a generation.
In 1790, 80% of Americans were living an agrarian life. Small farms were the rule. In 1950, less than 20% were farming. The majority, close to 60% worked in factories. In 2010, just over 10% were working in farming. In. . .