He was the one who taught people about the causes of suffering and their relief.
He sought answers to the problem of human suffering. He went to a yogi named Rajagaha and began an ascetic life. He left Rajagaha and practiced under two other yogi hermits who taught meditation. Then he moved on to become a student of yoga with Skr. Udraka Rāmaputra.
He kept moving on until he found his own path to enlightenment, but his teachers were all enlightened humans, designated to teach others. Buddha was the one who found the words to pave the way for others to find the freedom he discovered.