Adam was made in God’s image. God created Adam out of the dust of the earth, which God breathed life into. This makes man unique among creation. None of the animals were created out of the earth or made in God’s image. Adam served as an intermediary between God and creation.
Eve was created out of Adam. Eve was not a separate creation from Adam, but rather an extension of Adam. Eve served as a helper and companion to Adam, because the animals were to far beneath Adam to be his companions, and God was to far above to be his companion.
The serpent was the embodiment of evil. He temped Eve by appealing to her pride. When discovered, the serpent was punished by God to crawl on its belly and forever be the enemy of mankind.