The key figures in the story of the Argonauts include Jason, the leader, who seeks the Golden Fleece; Hera, who aids him; Atalanta, the skilled huntress; and the Centaur Chiron, who mentors heroes. Each character contributes unique abilities and traits to the quest, emphasizing themes of courage, loyalty, and teamwork. Their adventures encompass challenges that test their strengths and resolve, providing rich narratives of heroism in ancient Greek mythology.