Or, was she important to Paul's Christian life?
Search Acts and all of the epistles to see how often and passionately she was mentioned by the early church.
Here is the level of passion about Mary in the early church:
Acts 1:14 These (the Apostles) all continued with one accord in prayer and supplication, with the women, and Mary the mother of Jesus, and with his brothers.
Any other mentions of her in all of the instructions about the church and church history and church function found in the epistles???
There is no problem with the Church officially defining a doctrine which is not explicitly in Scripture, so long as it is not in contradiction to Scripture.
The Catholic Church was commissioned by Christ to teach all nations and to teach them infallibly—guided, as he promised, by the Holy Spirit until the end of the world (John 14:26, 16:13). The mere fact that the Church teaches that something is definitely true is a guarantee that it is true (cf. Matt. 28:18-20, Luke 10:16, 1 Tim. 3:15).