This was the British Invasion, and the Beatles were its undisputed leaders. In 1963, the Fab Four released their first U.S. single, "Please Please Me."
In the beginning, what set them apart was their new sound and look. The fact that they were from England at a time when all US pop music was homegrown made them a little exotic.
The fact was that these guys actually had talent and used their popularity as a platform to experiment with new sounds.
The girls went crazy for the Fab Four and every teenaged guy tried to capitalize on that look.