It was understood by the Church since Apostle Paul's time, sir. Augustine was a follower of Paul's teachings. Jesus also implied we are all with sin.
John 8:7 (New International Version)
"But Jesus bent down and started to write on the ground with his finger. When they kept on questioning him, he straightened up and said to them, "If any one of you is without sin, let him be the first to throw a stone at her."
Jesus was quiet confident that there would be no stone throwing that day. When Adam sinned, we all sinned. For the sin nature is passed down in the flesh we inherited from our original father. That is why Jesus could not have a human father!
Romans 7:17-18 (New American Standard Bible)
"So now, no longer am I the one doing it, but sin which dwells in me.
For I know that nothing good dwells in me, that is, in my flesh; for the willing is present in me (soul), but the doing of the good is not. "
Sticking with fundamentals, GeneZ