Look at what Paul says here about Adam's sin. First, he says in verse 12 that through one man sin entered the world. Sin was not in the world when God first made us. First we had to break from God. Sin entered by Adam because Adam was the one who ate the forbidden fruit. Romans 

says that it was not only sin that entered into the world by Adam, but death. Death came as a result of sin… Just as there was no sin in the world when God made it, so also there was no death in the world.

WSC Q17: Our Fallen Estate

The idea of imparting a body of truth (rudiments of the faith) is found repeatedly in scripture under many different terms and descriptions. We are not given a complete catechism or confession in the Bible. That is because we are to write our own according to the needs of the day. They must refute new heresies as they arise. Our Lord has called us to catechise in His church… to teach disciples the basics of the faith. Make the most of this instruction: memorise your Catechism, listen to the messages, and pray for the Spirit to work.