The Church does not hold to prima scriptura, a view popular with some apologists such as Dr. Scott Hahn. Instead, Scripture and Tradition are interconnected parts that lead to a single truth. Each serves the common good of spreading the Gospel and bringing men to Christ and Christ to men via the sacraments, especially the Eucharist.
Prima scripturists hold that because the OT existed first, it proves that scripture holds the place of primacy. This, however, is not necessarily as it appears. Though the OT was physically written before Pentecost occurred, the OT was at the service of the Christian Church to prove the veracity of Christ’s mission and proofs of divinity. It took the living witness of the Church to bring this truth to mankind.
There are many reasons to conclude that the Church as repository of Christ’s truth and the true faith is actually prime. There was no easy means for the scriptures to be written and disseminated until about 1400 years after Christ died, rose and ascended into Heaven. The Bible didn’t exist in a canonically settled form until the Church gave it one around 400 AD. Scripture and Tradition are both so bound to one another that separating them deforms them, and without the guidance of the Magisterium, sola scriptura leads to protestantism and sola traditio leads to radical tradtionalism, with its extreme logical end being sedevacantism.
In The Shepherd of Hermes, the patriarch was shown a very ancient woman by an angel. When the angel asked him to identify her, the man said she was a sybil. The angel replied that, no, she was the first thing ever created and the universe was created after her: She was the Church, the first idea of a creature existing in God’s Mind. (The Son and Holy Spirit don’t count, as they’re not creatures and they were of course first of all.) This is a private revelation and therefore not binding on the whole of Christianity, but it provides some real food for thought.