Granny above has it exactly correct. The Church teaches as a matter of dogma that Adam and Eve are two real people from whom we are all descendants.
**For the faithful cannot embrace that opinion which maintains that either after Adam there existed on this earth true men who did not take their origin through natural generation from him as from the first parent of all, or that Adam represents a certain number of first parents. **
(HUMANI GENERIS, Paragraph 37, Pope Pius XII, August 12, 1950)
Adam and eve are not myths.
In 1909, the Pontifical Biblical Council issued a decree interpeting the first chapers of Gensis as history, not myth. Remember that the author of Genesis 1-3 is God. The person (presumably Moses) who wrote Genesis 1-3 under the infulence of the Holy Spirit (God) used literary styles such as poetry and storytelling to transmit facts to us. God’s intent was not to provide man with a scientific account of the creation of the universe but to transmit truths to us about why we are here and how to make choices and trust God even when it is difficult to do so.
The facts and truths which God wishes us to know and which the valid authority of the Church established by Jesus Christ says that every Christian must believe, in laymans terms, are as follows:
*]God created all things at the beginning of time
*]Man was specially created
*]God created man male and female
*]All humans descend from a single original race (later defined as a couple by PIUS XII in Humani Generis)
*]Our first parents lived in a happy state of justice, integrity and immortality.
*]God gave them a command to test their obedience.
*]They disobeyed the divine command at the instigation of the devil, who took on the form of a serpent.
*]Our first parents fell from their state of innocence.
*]They were promised a future redeemer.
[/LIST]These are truths revealed to us by God in scripture, as taught by the Church which he established and gave sole authority to teach on such matters. The Church calls these de fide definita or definite truths. These thruths therefor, are not debatable. As always, God leaves individuals free to reject all or part of his revealed truth and waits eagerly for their return from doing so.
Phil Porvaznik has a good collection of material on this subject at philvaz.com/apologetics/p100.htm