"Priest" derives from "presbyteros". It is true that it also is used on occasion to describe Hebrew priests, as in Mark 15:1.
It is also true that the words shifted somewhat and the usage solidified sometime in late antiquity. Hiereus in modern Greek and modern context means Christian priest.
The point remains that to never translate "presbyteros" as "priest" regardless of context is misleading, because in Christian contexts "priest" is the best fit. To translate "episcopos" as anything but a "bishop" is outright lying.
The greek word in Mark 15:1 is not presbyteros it is archiereus
Translates
1) chief priest, high priest
2) the high priests, these comprise in addition to one holding the high priestly office, both those who had previously discharged it and although disposed, continued to have great power in the State, as well as the members of the families from which high priest were created, provided that they had much influence in public affairs.
3) Used of Christ because by undergoing a bloody death he offered himself as an expiatory sacrifice to God, and has entered into the heavenly sanctuary where he continually intercedes on our behalf.
Please check your greek. As I said before the greek language has a specific word for priest..there was no role of priest outlined in the NT church m, because the hebrew priesthood was a type of Christ..Once He had offered Himself up there was no longer a need for priest or sacrifice..
English (KJV) (Help) Strong's Root Form (Greek) Tense
And g2532 καί kai
straightway g2112 εὐθέως eutheōs
in g1909 ἐπί epi
the morning g4404 πρωΐ prōï
the chief priests g749 ἀρχιερεύς archiereus
Youngs literal translation
Mar 15:1 And immediately, in the morning, the chief priests having made a consultation, with the elders, and scribes, and the whole sanhedrim, having bound Jesus, did lead away, and delivered [him] to Pilate;