There is the 12 Apostles called by Jesus
Luke 6:12-16
Douay-Rheims 1899 American Edition
12 And it came to pass in those days, that he went out into a mountain to pray, and he passed the whole night in the prayer of God.
13 And when day was come, he called unto him his disciples; and he chose twelve of them (whom also he named apostles):
14 Simon, whom he surnamed Peter, and Andrew his brother, James and John, Philip and Bartholomew,
15 Matthew and Thomas, James the son of Alpheus, and Simon who is called Zelotes,
16 And Jude, the brother of James, and Judas Iscariot, who was the traitor.
So, you have Peter, Andrew, James, John, Philip, Bartholomew, Matthew, Thomas, James, Simon, Jude and Judas. That's twelve.
Christ clearly did not intend for his church to be limited to 12, or to die out with his 12 chosen apostles. That's where we pick up in Acts e.g. the Apostle Paul.
I don't see the problem.