or maybe we were never so unique and we are just now discovering it through the internet that allows us to find other like-minded people?
Hundreds of years ago, people would go through life only knowing others they'd met in person. This meant that most people would only be able to meet like a few hundred others in their life (unless you have some rare special job that took you traveling around the world). In that world, people would have all seemed unique as we'd all have met fewer people who were similar.