I always assumed it's peers as opposed to superiors. I.e. Your jury is not the king and queen but other commoners like you.
Ummmm..... the Magna Carta was not about protecting the commoners from the king. It was about protecting the peerage from the king. "Jury of peers" is a jury of other members of the peerage trying a peer. Commoners were not part of the program.
Because the defendant was a musician in this case.
Leonard French—a YouTuber and actual copyright attorney—does a good job covering the legal standards and issues here: https://youtu.be/t-tsw6Z4eHc.
A jury of random people can be confused and then convinced by lawyers. That's the way they like it, and that's the problem with jury selection - they chose people specifically because they are not knowledgeable.
To start: Not removing jurors simply because they're knowledgeable or have critical thinking skills.