The early church had apostles and prophets. Why not today?
Because the apostles and prophets are the foundation, and a foundation is laid once. We have their teaching in the New Testament.
An apostle in the New Testament sense was a witness of the risen Jesus, chosen by him. Paul calls himself the last to see the risen Lord. The church is built on the foundation of the apostles and prophets, with Christ as the cornerstone, and their teaching is preserved for us in Scripture. Every generation builds on it; none needs to lay it again.
19So then you are no longer strangers and foreigners, but you are fellow citizens with the saints and of the household of God, 20being built on the foundation of the apostles and prophets, Christ Jesus himself being the chief cornerstone;
Ephesians 2:19-20 (WEB) · context
21“Of the men therefore who have accompanied us all the time that the Lord Jesus went in and out among us, 22beginning from the baptism of John to the day that he was received up from us, of these one must become a witness with us of his resurrection.”
Acts 1:21-22 (WEB) · context
8and last of all, as to the child born at the wrong time, he appeared to me also.
1 Corinthians 15:8 (WEB) · context
3Beloved, while I was very eager to write to you about our common salvation, I was constrained to write to you exhorting you to contend earnestly for the faith which was once for all delivered to the saints.
Jude 1:3 (WEB) · context