This is a great question for the discussion board! Seabiscuit became a national hero because people LOVE an "underdog" story. Seabiscuit was short, clumsy, disheveled. He was not the typical Thoroughbred, especially in the world of competetive horseracing. However, there was potential for him because of his great speed. He also had a competitive spirit and a fire in his temperament! With a great jockey and a great trainer, Seabiscuit captured the hearts of America during a time that America was experiencing the Great Depression, a time of financial ruin and many homeless and destitute people. Times were very hard and many had lost all hope. They looked to anything to lift their spirits. According to eNotes:
Seabiscuit became a cultural icon, according to Hillenbrand, and offered hope to a generation of disadvantaged people: if he could overcome adversity and become a winner, so could they. From his initial outings in the dust of Tijuana to his grudge match with Triple Crown winner War Admiral, Seabiscuit epitomized the rags-to-riches American dream for millions of impoverished citizens who wondered whether the dream was still possible.
Seabiscuit's story is one of hope and determination. Even though he wasn't the typical Thoroughbred, he simply needed the right people around him to bring out the champion in him, and did they ever! Despite numerous injuries and setbacks, he was a great racing success story (eNotes).