Season 14 dealt with the aftermath of Apocalypse World Michael possessing Dean, and the gradual revelation that Chuck (God) had been manipulating events all along.
Major Lore Developments
Michael's possession of Dean and his eventual escape raised questions about the vulnerability of even the most experienced hunters. Jack's powers fluctuated dramatically — losing his grace, regaining it, and accidentally killing Mary Winchester in a moment of lost control. The season's most significant revelation came at the end: Chuck had been pulling strings throughout the entire series, treating the Winchesters' lives as a story he was writing. When Sam and Dean refused to follow his script (specifically refusing to kill Jack), Chuck snapped and unleashed every soul from Hell, setting up the final season.