Lynch was never named the Broncos starter. He never won the starting job, which makes him almost unique in NFL history. He did start some games, but only due to Trevor Siemian being injured, sucking, etc.
They named Brock Osweiler the starter for a game too, and if he had done great, they could have continued to keep him around and possibly named him as the starter. OF course he sucked. . . . But he was never named the Broncos starter like Case Keenum was last year or Joe Flacco this season.