The Canadian riches-to-rags comedy about a rich family stripped of everything began as a delightfully silly showcase for its cast, including Dan and Eugene Levy (who co-created the show), the ever-incredible Catherine O’Hara, and the surprisingly formidable Annie Murphy. But four seasons later, “Schitt’s Creek” has evolved right alongside its characters to become more confident and mature. Dan Levy, who also serves as writer and showrunner, finds a worthy partner onscreen in Noah Reid’s Patrick. Murphy more than holds her own as her spoiled Alexis lets herself open up. And the reliable team that is Eugene Levy and O’Hara build on decades of working together to make their married characters ring both true and deeply absurd.