Jeremiah's statement in 14:14 is about false Prophet's lies, and does not exists in the Lord's name.

Actually, Jesus did pick Mattias, through the Holy Ghost to Peter and the Apostles. The rock of revelation went through Peter as Jesus said he was the rock of revelation after his death. While the Lord came to Paul in revelation as well, He most certainly came to Peter to tell Peter he has chosen Paul. The Lord did not establish His Church on the foundation of anarchy. He is a God of order.
Moses chose one from each tribe to lead. He also chose 70 others. Jesus did the same thing. One Apostle from every tribe. Then, he said unto Peter, through you will I build my church. You are the rock of revelation. That verse meant he was the Prophet and leader of the Lord's Church. The Church of Jesus Christ. Yes, in those days, Jesus called Apostles first. This makes sense because why call a prophet when he was here on earth. However, I believe that the Lord called Prophet's in OT days from the leaders of each tribe of Israel and they were Apostles in OT days. They weren't called that using that term. But, nevertheless, there were 12 leaders as Moses and Joshua called to lead them into the promise land.
I can agree with you on the number of Apostles. It's not known how many there were. But, within the Apostles, was a quorum of the 12 Apostles. They hold the keys of the Kingdom. But, there is another quorum. The Presidency of the Church. They consist of Apostles with one being the Prophet and President with two or more councilors. So, at least 15 Apostles are possible making up both quorums. And, you are correct. Most people don't know that function even though it's clear in the NT that they are witnesses to the divinity of Jesus Christ and that He lives. They were commissioned to spread the Gospel to the four corners of the earth. They were given help to teach and preach the Gospel with the 70 special witnesses or evangelists. The people already understood teachers and what they were.
Could there be Apostles and Prophets today? Yes! But, there would have had to be an apostasy of the word and authority or priesthood first as Paul wrote. There was. Not just a little one but a very long one. The people in the meridian of time thought that the Lord would return very soon after his resurrection. But, that was just hope talking. Everything had to be polluted including the meaning and understanding of the priesthood. Paul explained the priesthood and clarified it as well to be a higher and lesser priesthood. They were clearly named after two righteous persons in the OT, Melchizedek and Aaron (brother of Moses, a Levite). Melchizedek was the higher priesthood after the order of the Son of God. That priesthood was in charge of the inner ordinances of eternal life like giving the Gift of the Holy Ghost while the order of Aaron was the outer ordinances such as baptism, like John the Baptist. These two priesthoods of authority to do the work of God (The priesthood is the power and authority of God to do His work on the earth) were eventually lost. Now, they basically don't exist in most Churches who say they are followers of Jesus Christ. But, they were lost and so was any authority of the Churches around the world. So, a restoration of all things, through a Prophet of God, called by God was necessary. These are the days of the restitution of all things of Christ as spoken in the NT. The apostacy has been overcome.
You might figure out I'm a member of The Church of Jesus Christ of Latter-day Saints.