[daniel1212]

You need to understand that the language of the Church was just forming just as the priesthood was..

I do understand that development, and thus it did not follow the distinction the use of hiereus consistently made in Scripture over 150 times to specify priests as they belonged to a special class, while never being used thusly for the elders/overseeers.

[Elsie]

I do understand that development...

I sure don't!

Why did the 'church' need to DEVELOPE; if it was the way JESUS set it up?

[annalex]

I do understand that development, and thus it did not follow the distinction the use of hiereus consistently made in Scripture

Yes, the use of "πρεσβυτερος" is less consistent than "ιερευς" as the different books of the New Testament were written at different stages of the development of Christian priesthood. This is why Douay uses both "priest" and "ancient" to translate it, depending on context.

This dual use of "πρεσβυτερος", both familiar and sacramental has seeped into our times. We familiarly call our priests "father"; "papa" is Italian for "daddy"; in Russian an endearment form of "father", "батюшка" ('batyushka) is used for priests.