Since its start 20 years ago, “American Idol” has helped many American idol celebrities get their start. In 2002, Simon Cowell, Paula Abdul, and Randy Jackson were the judges on Fox’s first episode of the show. Kelly Clarkson, who won the first season, became one of the show’s biggest successes. The show ended in 2016, but ABC brought it back two years later. This time, judges Katy Perry, Luke Bryan, and Lionel Richie was in charge. Still, the message was the same: you can follow your dreams, and “American Idol” could help you do it. Singers didn’t have to win to be successful; some of the most well-known stars didn’t…