How Do We Know that the Greeks Knew Who Kain Was?
Greek artists portrayed the Flood as a man named Kaineus being beaten into the earth by Kentaurs (Centaurs). Kaineus represents more than a single man for Kaineus means pertaining to Kain, or the line of Kain. Thus, during the Flood the entire line of Kain disappeared into the earth. To the Greeks, the Kentaurs represented that strange branch of humanity, the line of Seth. The family of Noah (the Greek Nereus, or Wet One), of the line of Seth, were the only ones to survive the Flood. All of the line of Kain disappeared into the earth. Thus, the way the Greeks remembered the Flood matches the Genesis account.
Furthermore, the Greeks deified Kain, the eldest son of Adam and Eve,
as Hephaistos, the eldest son of Zeus and Hera. For more details on
the correspondence between the first family of Genesis and the first
family of ancient Greek myth/art, see an eight-page summary of the meaning
of ancient Greek myth/art here.

The vase-artist of the partially damaged Francois Vase, ca. 550 BC, writes the names of the Kentaurs (the line of Seth), and the name of the man being pounded into the earthKaineusthe line of Kain.
Next: Two Vases Depict the Essence of Ancient Greek Religion