The ancestors of Scotch Collie are ancient herding dogs – including the Roman Cattle dogs, Viking Herding Spitzes and Native Celtic dogs. Another probable ancestors are Irish and Gordon Setters.
In 1700s there was a Collie type of dog living in the Scotland, which resembles the Collie we know today. In their native land they were used to herd farm animals, but also for guarding and hunting. Scotch Collie was imported to the America in the 1800s to help farmers.
That caused, that some people and kennel clubs started to breed them for the showring. And as you can probably guess, in the showring, the most important thing is the appearance and not the herding ability.
The show Collies lost the hardworking temperament and they probably lost some of the intelligence as well. The most important thing was, that they make good companions and they look good. I am not saying that the show and lets say „city“ collies were stupid, not at all, but they were different from the original breed.