Question: If the Apostle Paul is considered the most important figure of the apostolic Age, is it because of his supernatural conversion which affected more than the other 11 Apostles?
Yes, his conversion was instigated by the Risen Lord, and his intense intellect and motivation were needed to be harnessed for God’s Work!
Paul's ability and learning made him at that time the most learned of the young rabbis (teachers). In fact in his testimony before King Agrippa, (Acts 25 and 26), he made a point of mentioning that he had been taught by Gamaliel, who was one of the most revered teachers of the Law ever in Israel. His head knowledge was beyond dispute, and together with his even more important quality, (his heartfelt dedication), led him to persecute to death the early Christians. These very qualities, (particularly the Lord's knowledge of his sincere and dedicated heart), led to that most favoured of pronouncements from the Lord; "he is a chosen vessel"! (Acts 9:15). Also, as shown in his testimony before King Agrippa; Paul showed his constant contact with the Risen Jesus; and that his mission was guided and adjusted over time; see below and Apostle Paul's Accusers.
John the Baptist, Jesus and the Apostle Paul berated the Jewish Hierarchy of the day for adhering to the Pharisaic writings, instead of the Originals given to Moses, known as "Biblical Judaism". It is recorded and well known by the Jews, that the Pharisees in particular were "very flexible" in their interpretations of Torah, and this is confirmed by the Qumran Scrolls. Of the main 'schools', or Groups of the day, the Pharisees, the Sadducees and the Essens; the Pharisees became dominant, and at the time of the destruction of the Temple in AD 70, only the "Judaism of the Pharisees", known as "Rabbinic Judaism" prevailed! This grew, and by AD 300, all the Pharisaic Interpretations of the original over centuries of “study by Jewish Sages” had been tabulated in the "Mishnah", purported to show the “original Scriptures”, with the Pharisaic “interpretation”. See: Jewish Scriptures: This is the basis of "Modern (Orthodox) Judaism". See: