Symbolism, Imagery, Allegory
The snakes that Hera places in Heracles' cradle instantly became the two most famous snakes in the world. If you are a snake, you probably want to be related to the snakes that slithered into baby Heracles' bassinet. Sure, your ancestors were strangled to death by the infant hero's tiny hands, but no one ever forgets those giant snakes. For thousands of years, artists have been capturing them in painting and sculptures like this one. Heracles' first great feat on earth was to treat these snakes like his toys. When even the great Hera couldn't kill he baby hero, everyone realized that he was a pretty important dude.
Whenever we see snakes in literature or mythology, our ears perk up a bit and our antenna starts to buzz. Snakes remind us of a primal, primeval time when dangers lurked everywhere and things like Velociraptors roamed the earth. They also remind us of a famous story from the Old Testament in which a savvy snake convinces a lady named Eve (according to the Old Testament, she's the first lady) to eat the apple of knowledge. Whenever a snake shows up in literature or mythology, we get the feeling that trouble is around the corner.