To answer that question we need to know what the first century church looked like.
The closest thing we have to explaining the first century church, other than the New Testament is the
Didache. It is supposed to be the oldest non-Canon writing of the early church.
We can see that they Baptized in the Name of the Father, Son, and Holy Spirit and that they baptized in "Living Water" (which many scholars take to be immersion in a river or lake), but allowance was made for baptizing in other water and by pouring water three times. Chapter 7.
They fast on Wednesday and Friday, instead of Monday and Thursday (like the hypocrites do). Chapter 8
They took the Thanksgiving Meal (Eucharist) and it was given only to those who had been baptized. Chapter 9
They said a Prayer after the Eucharist meal thanking God for "Spiritual Food and Drink". Chapter 10
They were to welcome fellow Christians. Chapter 12
They financially supported "their prophet" and the poor, Chapter 13
They assembled on the "Lord's Day", broke bread, offered Thanksgiving, and confessed so that their sacrifice will be pure. Chapter 14
note-A Catholic will tell you that Sacrifice means the Eucharist but that doesn't really fit the context or scripture in light of Romans 12:1 and Hebrews 13:5, the sacrifices we bring are a living sacrifice of ourselves and our praise. Plus, we as Christians bring no sacrifice to the alter, we aren't Christians because of our sacrifice, we are Christians because of Christ Sacrifice.
They appointed their own Bishops and Deacons. Chapter 15
They waited faithfully for the Coming of the Lord, Chapter 16
So we see, not many of our 21st century churches are exactly like the 1st Century church.
Most of us aren't instructed to fast on Wednesday's and Friday's.
Infant baptism by dripping some water over the baby is the most common form of baptism instead of immersion or pouring
Most churches do not take the Lord's Supper when they meet on the first day of the week. For centuries even the Catholic church didn't offer communion to the congregation weekly. It only became the weekly part of the Catholic Mass after the Reformation because the reformed churches were taking it weekly. Most American Evangelical churches take communion 4 times a year or 12 times a year. I understand that
the practice is varied among Lutherans', Anglicans, and Presbyterians.
Most churches today do not appoint their own bishops (elders) and some don't even appoint their own deacons. More often than not a Regional Bishop/Elder will appoint the bishop/elder/pastor for local congregations under their jurisdiction.