If you listed everything you knew about the serpent in Genesis, one of the first things you'd probably mention is that the serpent was a physical manifestation of the Devil himself. Those familiar with the Genesis story typically believe that Satan took the form of a snake in order to trick Eve and Adam into sinning, thus forcing God to kick them out of paradise. But this is wrong. In reality, the authors of Genesis never intended the serpent to be Satan. How do we know? Satan wasn't yet an idea at the time Genesis was written.
Per the Biblical Archaeology Society, "Satan" didn't emerge as a concept until the second and first centuries BCE. Genesis was written several centuries before this; perhaps as early as 950 BCE, according to Britannica. This is a bit confusing, as the term "satan" does appear throughout the Hebrew Bible, but in ancient Hebrew, "satan" simply meant "adversary" or "accuser." Numerous characters in the Old Testament are referred to as "the satan," but it wasn't until later in the Jewish tradition that the idea of a powerful lord of darkness known as "Satan" was created.
When the idea of Satan did ultimately emerge, many Jews and Christians reinterpreted the story of the Garden of Eden. Under the new (now common) interpretation, the serpent in the Garden was Satan himself — even though this is never stated in Genesis.
