The problem with this is that Mathias was named among the original 12 to replace Judas before Paul became an apostle.
Second, the bible speaks of more apostles then just the original 12, as Luke 10:1 shows the Lord appointed 70 more. And other scriptures name other apostles, as Timothy was an apostle as well.
That is of course true. The twelve elected Mathias; but IMO Jesus overrode them and elected Paul.
If you think the eleven were incapable of such an error; remember that they had not yet received the guidance of the Holy Spirit; and the gospels record far worse errors.