The following is speculation. But I believe it aligns with the Teachings of the Catholic Church and with science.
Question: Doesn’t human evolution contradict the Biblical account of the the creation of man by God?
Answer: No. CCC 366 The Church teaches that every spiritual soul is created immediately by God - it is not “produced” by the parents…
Pope John Paul II in his Message to Pontifical Academy of Sciences October 22, 1996 said,
Pius XII stressed this essential point: if the human body takes its origin from pre-existent living matter the spiritual soul is immediately created by God (“animal enim a Deo immediate creari catholica fides nos retinere inhet”; Encyclical Humani generic, AAS 42 , p. 575).
Catholic Information Network (http://www.cin.org/jp2evolu.html)
Therefore, Adam and Eve’s soul was created directly by God. The body evolved by processes put into effect by God.
Question: But science says that man descended from apes, while the Bible says that man was formed out of dust, Genesis 2:7 “And the LORD God formed man of the dust of the ground, and breathed into his nostrils the breath of life; and man became a living soul…”
Answer: Science also says that originally all life came fom some primordial mud. In comparison to God, we are all bits of mud and dirt. The Biblical Narrator may have been referring to some apes as a bit of clay and portrayed God as taking a bit of genetic material from this ape to make Adam.
Note also, that all animals were created out of the ground, Genesis 2:19 “And out of the ground the LORD God formed every beast of the field, and every fowl of the air; and brought them unto Adam to see what he would call them: and whatsoever Adam called every living creature, that was the name thereof…”
Answer: Yes. Man’s propensity to sin.
Question: How does any of that work exactly?
Answer: No one knows that answer. But we can speculate for instance, that an ape existed which had evolved to a certain level of intelligence. God took a little dust, a male infant (or an adult), breathed into it and made it into the first man. Then God took a female from the same species and made the first woman in the same way. He then put them in the Garden of Eden.