It's hard to imagine how and why the job interview became the normal way to get a job. Exactly when did the job interview become standard practice?
Once humans advanced beyond the hunter-gatherer stage of cultural development and began to assign professions to certain individuals, the passing on of these roles from generation to generation was the norm. In short, people were born into their job. If your father was the blacksmith, you learned to become the next blacksmith, and so on.
Occasionally, a "job opening" would emerge when there was no "heir" available to whom a tradesman could pass along his knowledge. An apprenticeship opening would arise and a youth would move in with an artisan and learn his craft. These were not quite "jobs" per se and in many cases amounted to a form of indentured servitude. However, the practice of apprenticeship goes back all the way to the Babylonian Code of Hammurabi (1792-1750 BC).
With the industrial revolution and the opening of large factories in America, job openings became plentiful. However, a job interview consisted of showing up at the door of the factory and hoping to get picked on that particular day.
It wasn't truly until the 1920s that there were enough college-educated individuals entering the workforce that employers started to realize they could be a bit more selective. But the man who "invented" the modern job interview is probably a name familiar to you: Thomas Edison.
As the story goes, Edison would get hundreds of applicants whenever he was seeking to add someone to his workforce. However, Edison was a genius and became increasingly frustrated that the college graduates who met with him seeking employment always seemed to lack knowledge comparable to his own.
Edison created a "test" for all prospective employees in the form of a series of questions of general knowledge. Some of these questions related directly to the position that the applicant was seeking, while others were more esoteric and related to topics such as world geography or literature. It’s unlikely that more than about seven percent of all applicants could pass Edison's test.
Newspapers of the day picked up the story and other captains of industry, perhaps wanting to emulate Edison, began using employment questionnaires of their own. The rest, as they say, is history. Over time the winnowing process of applicants has evolved into the system of hiring that we have today.