I think the easier answer is that the whole story is allegorical (an dthe original authors really did not associate the snake with Satan, with it just being a later allegorical gloss. Again, it is a Jewish book, and they see Satan as a faithful servant. If the whole story is allegory, than adding a new allegory to it by introducing the Christian character of Satan isn't at all invalid.
It's only when you interpret it literally that the snake's "real identity" takes on any importance.
I do like the part about creating enmity between snakes and women, as I can easily imagine the original author struggling to come up with a reason women are so afraid of snakes. It's an interesting aside into the territory of ancient sexism.
*************
M*W: Allegory? Yes. It is even allegory of allegory of allegory, and the allegories become confused to say the least, because they represent many different characters of myth.
The ancients associated serpents with women (goddessi), because of the serpent's alleged healing powers from the shedding of it's skin bringing a "new birth." And women, of course, are associated with birth.
It is my belief that the idea of the "original" serpent, you know, the one in the "Garden," etc., etc., (which I believe represents the zodiac), was taken from the Constellation Serpens.
According to Ian Ridpath: "In mythology, Ophiuchus was identified as the healer Asclepius, son of Apollo, although why he appears to be wrestling with a serpent in the sky is not fully explained. His connection with snakes is attributed to the story that he once killed a snake that was miraculously restored to life by a herb placed on it by another snake. Asclepius subsequently used the same technique to revive dead people. Snakes are the symbol of rebirth because they shed their skins every year."
"The Serpent Holder is actually two constellations: 1) the Serpent-Holder itself surrounded on both sides by 2) the Serpent (whose head is to the left of the Serpent Holder and is called Serpens Caput, and whose tail is to the right of the Serpent Holder, Serpens Cauda). Originally, however, the two constellations were conceived of as a single unit."
Allen says: “Of the four stellar Snakes this preeminently is the Serpent, its stars originally being combined with those of Ophiuchus, ... but it now is catalogued separately, and occasionally divided into Caput and Cauda on either side of the Serpent-holder.”
"The Serpent-Holder constellation is one of the largest, if not the most vast one, in the night sky. Perhaps it was one of the most important. If one finds it in the sky, the Serpent-Holder looks overwhelming. A further key to its importance may be its position in the night sky, for it looks as though it could be part of the zodiac."
"As stated elsewhere, the zodiac has been considered important, because the sun and planets (seem to) travel through the constellations of the zodiac, and knowledge of when certain constellations would appear on the horizon at specific times of the year provided a "calendar" by which agricultural peoples could determine planting, harvesting, etc.."
"In addition, and related to this fact, watching the sky was, in an earlier form, an important religion among certain peoples in prehistory, concerned with the zodiacal constellations, as well as the sun, planets, and moon which (from earth seem to) travel through them. Present-day astrology is a remnant of just such religions."
Rey states: "An odd thing about the Serpent-Holder is that it reaches into the zodiac, yet is not by tradition counted among the zodiacal figures, possibly because there would then be 13 constellations instead of 12." This information is extremely interesting, especially because if one looks at the ecliptic, the imaginary line through which the zodiac figures go, one finds that Aries the Ram (which is part of the zodiac) does not have even one star reaching across that line, whereas the Serpent-Holder's leg very definitely does."
"Might the Serpent-Holder not have been a 'member' of the zodiac at one time? And why would 13 constellations have been so bad? (Twelve constellations, or twelve zodiac signs, represent the twelve-month calendar, but the twelve-month calendar is not set in stone.) There are other things to consider as well about this whole problem. At one time Libra, the Scales, and Scorpio, the Scorpion, were part of one constellation, so if the Serpent Holder was in the zodiac at that time, there could still have been twelve constellations comprising the zodiac."
Barbara Walker, in her encyclopedia says: "'Eve' in Hebrew was "YHWH, yod-he-vau-he, ... from the Hebrew root HWH, meaning both 'life' and 'woman'--in Latin letters, E-V-E. With the addition of a Y (yod), it amounted to the Goddess's invocation of her own name as the Word of creation, a common idea in Egypt and other ancient lands" (288). She would thus be saying, "I, Eve," YHWH."
According to Walker, the Hebrew YHWH means 'Eve,' 'life,' and 'woman.'
According to Howey the Arabic means 'life' and 'serpent,' and in the name 'Aesculapius' are contained the concepts 'Serpent' and 'Teacher.'
Further, under 'Serpent' Walker states: "Gnostic accounts of the Eden myth used the Aramaic pun identifying Eve, the Teacher, and the Serpent: Hawah, Mother of All Living; hawa, to instruct; and hewya, Serpent. Eve's name in Arabic still combines the idea of 'life' hayyat with the name of the serpent (Hayyat)."
M*W wonders if the symbolism of the missing 13th constellation could have been the one signifying that one which was 'cast out of the Garden' (zodiac)? Could the various allegories of the constellations have been viewed in new ways by later cultures, therefore, causing all the confusion we have about it today? Who was right? Well, let's say they all were. The vision is really in the eye of the beholder, and they all gave us great myths. What we need to remember is that's what they are... myths. We need to enjoy them for what they were and still are (ancient entertainment), and not try to validate them as religious fact.
References:
Allen, Richard Hinckley:
Star Names and Their Meanings. "Many theories have been propounded for the birthplace and time of formation of this; but there now seems to be general agreement of opinion that..." (more) (I'll provide a proper citation for this later.~M*W).
Howey, M. Oldfield:
The Horse in Magic and Myth: A rich compilation of legend and lore from classical mythology, the Bible... ISBN13: 9780486421179 (Sorry, but I couldn't find biblio details).
H. A. Rey.
Find the Constellations. Houghton Mifflin, 1954. Several revised editions, most recent edition in 1988.
Ian Ridpath and Wil Tirion (2007).
Stars and Planets Guide, Collins, London. ISBN 978-0007251209. Princeton University Press, Princeton. ISBN 978-0691135564.
Walker, Barbara:
The Woman’s Encyclopedia of Myths and Secrets Harper & Row, San Francisco, 1983.