"And, incidentally, you're wrong. Adam and Eve were sinless before the Fall."
Did Adam and Eve walk the earth? Then how is he wrong?
Did Adam and Eve walk the earth? Did they not sin? Then how is he wrong?
She said that no sinless person ever walked the earth. Adam and Eve were sinless persons until the Fall, and they "walked the earth" before the Fall, hence it's false to say that the only sinless person who ever walked the earth was Jesus.
If Adam and Eve had not sinned against God, you would be correct.
But in Catholic as well as Protestant Scripture, our first parents both sinned.
No man walked the earth without the stain of Adam's Original Sin but Jesus Christ.
The interesting thing is this used to be stressed in Catholic catechism. Lately, not so much.