The TBS original is an anthology series, which means each season serves as a sort of standalone, giving the creators the option to create an entirely new scenario and characters to play out while keeping the same actors and general roles. American Horror Story is a good example of this, where each season can be watched individually of the other instead of needing to be watched in subsequent order.
In an interview with Variety, creator Simon Rich said that "the beauty" of running the show with this format is that it allows him to make these drastic changes to the title. Season 2 of Miracle Workers was based on a short story that had yet to be published, and Simon said he and the writers used it as a very loose guideline for the structure of the season.
“The short story is just a jumping off point. I purposefully asked the writing staff to not read it because I don’t want anyone to feel like they’re tied to any text,” he said. “Then we just put up pictures of the cast on the wall and stared at their faces for weeks and months; we moved them around. That’s what so fun about this particular show: We have such an amazing cast, it’s not about, ‘How do we squeeze this guy in?’”
Similarly, Oregon Trail takes a similar route that the Dark Ages season of Miracle Workers did. This is just a new season for the show, featuring many of the same cast members in entirely new scenarios.