Titus 1:5-7 shows that presbuteros (senior/elder) or episkopos (superintendent/overseer) refer to one office, with the former title corresponding to the mature leadership of the person, and the latter to his function.
.the evidence both from the New Testament and from such writings as I Clement, the Letter of Polycarp to the Philippians and The Shepherd of Hermas favors the view that initially the presbyters in each church, as a college, possessed all the powers needed for effective ministry. This would mean that the apostles handed on what was transmissible of their mandate as an undifferentiated whole, in which the powers that would eventually be seen as episcopal were not yet distinguished from the rest. Hence, the development of the episcopate would have meant the differentiation of ministerial powers that had previously existed in an undifferentiated state and the consequent reservation to the bishop of certain of the powers previously held collegially by the presbyters. — Francis Sullivan, in his work From Apostles to Bishops , pp. 224
"So far as i know, it was only ca. 200 that the term “priest” started to be applied to the bishop and only still later was it applied to the presbyter. This observation explains why some Protestant churches which insist on using New Testament language alone refuse to call their ministers priests. When in the post-New Testament period the language of priesthood did begin to be applied to the bishops and presbyters, it brought with it a certain Old Testament background of sacrificing Levitical priesthood. The introduction of that language was logically tied in to the development of the language for the eucharist as a sacrifice. (...I think there were sacrificial aspects in the early understanding of the eucharist, but I have no indication that the eucharist was called a sacrifice before the beginning of the second century.) When the eucharist began to be thought of as a sacrifice, the person assigned to preside at the eucharist (bishop and later presbyter) would soon be called a priest, since priests were involved with sacrifice." — Raymond Brown (Sulpician Father and a prominent Biblical scholar), Q 95 Questions and Answers on the Bible, p. 125, with Imprimatur.
Catholic writer Greg Dues in “Catholic Customs & Traditions, a popular guide” states, "Priesthood as we know it in the Catholic church was unheard of during the first generation of Christianity, because at that time priesthood was still associated with animal sacrifices in both the Jewish and pagan religions."
"When the Eucharist came to be regarded as a sacrifice, the role of the bishop took on a priestly dimension. By the third century bishops were considered priests. Presbyters or elders sometimes substituted for the bishop at the Eucharist. By the end of the third century people all over were using the title 'priest' (hierus in Greek and sacerdos in Latin) for whoever presided at the Eucharist."
>> So far as i know, it was only ca. 200 that the term “priest” started to be applied to the bishop and only still later was it applied to the presbyter. <<
Ludicrous. The word, “priest” is simply the Anglicization of the word, “presbyter,” which, as you know, appears several times in the bible.
Note: the notion of a non-Christian priest became so abstract by renaissance England, that English translations of the bible used the word to also describe “hierus.” In Latin and Greek, “presbyter” and “hierus” are separate words.