“That Sacred Tradition preceded New Testament Sacred Scripture and that the early Church relied exclusively on the oral Sacred Tradition cannot be disputed.”
This would have ended sometime before the destruction of the Jewish temple for the majority of the New Testament, with only John contributing with Revelation and his Gospel before the end of the first century. You forget, the Apostles were alive and everything they said was authoritative. Yet, since they considered themselves scripture-producers, it’s illogical to think they would leave the most important parts of Christianity up to an oral tradition, so that any Tom, Dick or Autolycus can claim to be spreading something important through word of mouth. Instead, at the end of the first century, we have it on record Ignatius, Polycarp and others all quoting from the vast majority of the New Testament scriptures, and not making arguments like “according to this doctrine which was passed orally from Peter all the way up to me...”.
The Apostles, the Disciples and their students and converts had spread the Gospel from India, to Russia and the Balkans, to Spain and North Africa by the end of the first century. Not all Apostles wrote and not all writings attributed to them are inerrant or original. Also consider that Mark and Luke were not Apostles or even eye witnesses, yet the New Testament captures what they learned through the Traditions.
Peace be with you