Q - Adam and Eve are not considered saints. Could it be that the first man and woman, our first parents, are still in Purgatory because of the seriousness of the first sin?
A - Thanks for the question. The Catechism gives us a clue to what happened to Adam and Eve after their death (emphasis added):
635 Christ went down into the depths of death so that "the dead will hear the voice of the Son of God, and those who hear will live." Jesus, "the Author of life", by dying destroyed "him who has the power of death, that is, the devil, and [delivered] all those who through fear of death were subject to lifelong bondage." Henceforth the risen Christ holds "the keys of Death and Hades", so that "at the name of Jesus every knee should bow, in heaven and on earth and under the earth."The second part of paragraph 635 from the Catechism is a quote from an ancient homily for Holy Saturday.
Today a great silence reigns on earth, a great silence and a great stillness. A great silence because the King is asleep. The earth trembled and is still because God has fallen asleep in the flesh and he has raised up all who have slept ever since the world began. . . He has gone to search for Adam, our first father, as for a lost sheep. Greatly desiring to visit those who live in darkness and in the shadow of death, he has gone to free from sorrow Adam in his bonds and Eve, captive with him - He who is both their God and the son of Eve. . . "I am your God, who for your sake have become your son. . . I order you, O sleeper, to awake. I did not create you to be a prisoner in hell. Rise from the dead, for I am the life of the dead."488
The tradition of the Catholic Church is that after the Resurrection and Ascension of Jesus, Adam and Eve were taken into heaven with Christ. In fact, through many years, their memorial was celebrated in the Church on December 24.
So they are, in fact, considered saints.
I hope this helps.