Acts 1:20-26 makes it very clear who were the apostles:

“For,” said Peter, “it is written in the Book of Psalms: “‘May his place be deserted; let there be no one to dwell in it,’ and, “‘May another take his place of leadership.’ Therefore it is necessary to choose one of the men who have been with us the whole time the Lord Jesus was living among us, beginning from John’s baptism to the time when Jesus was taken up from us. For one of these must become a witness with us of his resurrection. So they nominated two men: Joseph called Barsabbas (also known as Justus) and Matthias. Then they prayed, “Lord, you know everyone’s heart. Show us which of these two you have chosen to take over this apostolic ministry, which Judas left to go where he belongs.” Then they cast lots, and the lot fell to Matthias; so he was added to the eleven apostles.

It's clear as day that apostles, or emissaries, that is, people who were responsible for spreading the message and eligible for community leadership had to have been eyewitnesses (and were twelve).

But yes, ever since Paul started to use that title, even that word was corrupted. Nowadays, many pastors (especially in Africa) call themselves apostles. Lol.