I am not sure I understand. You do not understand the biblical rationale for elders?
If that is what you are interested in, you can see the office of elder throughout the Word of God. For instance, in Acts 20, Paul famously called for the elders of the Ephesian church:
Acts 20:17, "From Miletus he sent to Ephesus and called for the elders of the church."
Acts 14, Paul and Barnabas appointed elders in the churches: "So when they had appointed elders in every church, and prayed with fasting, they commended them to the Lord in whom they had believed."
Titus 1 - gives the qualifications for elders, "5 For this reason I left you in Crete, that you should set in order the things that are lacking, and appoint elders in every city as I commanded you—6 if a man is blameless, the husband of one wife, having faithful children not accused of dissipation or insubordination. 7 For a bishop must be blameless, as a steward of God, not self-willed, not quick-tempered, not given to wine, not violent, not greedy for money, 8 but hospitable, a lover of what is good, sober-minded, just, holy, self-controlled, 9 holding fast the faithful word as he has been taught, that he may be able, by sound doctrine, both to exhort and convict those who contradict."
And of course we have the council of Jerusalem in Acts 15 when all of the elders of the church convene to deal with doctrinal difficulties.
The New Testament has many passages that deal with elders, those are just a few.
But it would be a mistake to think that the New Testament is the origin of the office of elder. In the Old Testament, we see that the elders are often mentioned when it comes to shepherding God's people.
Numbers 11:16 "So the LORD said to Moses: 'Gather to Me seventy men of the elders of Israel, whom you know to be the elders of the people and officers over them; bring them to the tabernacle of meeting, that they may stand there with you."
All throughout the Old Testament, you read of elders coming to help adjudicate issues of judgments among the people, and the New Testament continues that office.
If you hold to the London Baptist Confession - you can review Chapter 26 when it comes to the officers of the church from a Baptist perspective.
Presbyterians see elders as having a role beyond that of the local church, but insofar as obligations to shepherding the local congregation, Confessional Baptists and Presbyterians are fairly similar.