There are many different views on Adam and Eve. You’ve got historical vs literary. Within historical, you’ve got de novo creation (with other humans already evolved) vs being born from the existing population. There may be other options as well.
I don’t think we can know what really happened. The main points of the passage are easy to see, regardless of which view you take.
I personally lean toward historical, born into a population and called out by God… I can’t rule out a de novo creation of Adam and Eve amidst an existing population though.
Natural selection would occur as Adam and Eve’s children are born, just like it does today.