But what did 1st century presbyters do? The koine Greek had a word for priest (iereus) but didn't apply it to prebyters. By definition, a iereus is the one who offers sacrifices and sacred rites.
The root word ieros means that which is sacred or consecrated to deity, as in iera grammata, sacred scriptures (2 Tim 3:15), something that is revered.
No such thing was ascribed to presbyters. I don't think there is one single instance in the New Testament (which uses the word presbyter 49 times) where the priestly (i.e. consecrated rites) are ascribed to a presbyter.
This new Christ-priesthood is referred to in the New Testament (I Peter 2:5, 2:9...]
Yes, 1 Peter is a late 1st century or an early 2nd century book, and, more importantly, it is addressed to the Christians and not presbyters in particular, with a message that it's good and desirable to suffer (1 Pet 2:21), and that doing so will make them acceptably to God (1 Pet 2:20), a la Jesus style.
and in that act of consecration, an act of sacrificial offering, they indeed become both the ones offering the they become "the holy priesthood."
It does seem, though, that all the local churches that arose in the first centuries AD and their historic descendants, whether they are Catholic or Orthodox, Assyrian Church of the East, Chaldeans, Copts, Calcedonian or non-Calcedonian, etc. --- they all had, and still have, a deacon-priest-bishop polity, and they all have a Mass or Divine Liturgy with the Eucharist regarded as a Sacrifice: eternal and accomplished by Christ. Celebrated by priests. Don't they?
If you know of any churches with an early (1st -3rd century)and continuous existence, who differ from this pattern, of course I'd be interested inhearing about them.