Acts 1:24-26
Then they prayed and said, ‘Lord, you know everyone’s heart. Show us which one of these two you have chosen to take the place in this ministry and apostleship from which Judas turned aside to go to his own place.’ And they cast lots for them, and the lot fell on Matthias; and he was added to the eleven apostles.
There is nothing to suggest that the lot falling on Matthias was not the mind of Christ speaking, and indeed to the contrary the witness of Acts is that this was prayerful and appropriate. Remember of course at this time Saul was not what one might perceive as available for selection.
Whilst the witness of Scripture is silent on Matthias, there is some evidence that he was influential in the establishment of the Church in Capadocia which is a place that many who study Church History will be familiar with. We certainly do not have the evidence to support the suggestion that Matthias come to nothing.
Paul, however, clearly achieved a great deal, and because to the extent of his travels, and the regions in which he travelled, and because he had enough time under arrest to write extensively, and his letters were preserved and cherished, means that we are very familiar with his thinking, and his great work. His own understanding is that he was sent (
apostolos) to the Gentiles, and I don't think he saw himself in any way second fiddle to the Galilean Fishermen and others who made up the 12, I am not totally convinced that he numbered himself among them. The criteria in Acts was not likely to include Paul.
Acts 1:21-22
So one of the men who have accompanied us throughout the time that the Lord Jesus went in and out among us, beginning from the baptism of John until the day when he was taken up from us—one of these must become a witness with us to his resurrection.’
I don't believe that the case has been made that the Church got in wrong in selecting Matthias. I have no need to make Paul one of the twelve in order to esteem and value his contribution to the ongoing life of the Church. He has much more to offer us.