Who was Icarus and how is he important? Could Icarus be a symbol for something?

Icarus was the son of Daedalus, the master inventor in classical myth. Among Daedalus's inventions was the labyrinth that held the Minotaur. While imprisoned in a tower, Daedalus made two sets of wings, held together with wax. Daedalus taught his son how to fly with them, and they planned their escape. Unfortunately, Icarus flew with them but ignored his father's warning to not go too high—too close to the sun—which would melt the wax, or too low, which might cause the feathers to get too wet with sea water. Icarus did fly closer to the sun than the wings could bear and fell into the ocean and died, in an area called the Icarian Sea, between Turkey and Greece.
In Auden's poem, as in literature since the classical age, Icarus is a figure of one who is defeated by his own hubris. Auden describes the minor presence of Icarus in Bruegel's painting, in which scenes of everyday life are featured. In a corner of the painting, Icarus is seen splashing into the ocean while everyone else is preoccupied by their own affairs. Symbolically, the painting, and Auden's poem, suggests that individual tragedies are often overlooked by humans, who, in the midst of their quotidian lives, are indifferent to the suffering of others.