It derives from the enlightenment era where basically the preconceived notion that people were born with their knowledge and abilities was challenged. It was a derived for those middle class men of the time who were attempting to challenge the authority of the nobility and their dominance over the judicial and legal systems. Previously, the trials were by a noble or a group of nobles who passed down a judgement, while the concept of a jury of your peers was intended to remove prejudice and class dynamics from judgement. In the modern age this means any random people but originally it truly was a jury of your peers, being wealthy, highly educated men.

In modern democracies, the idea of a jury removes the idea of nobility and enforces the idea that the citizen matters, that government is first and foremost a servant of the people, a slave to the citizens will.