When did the administrative part of Christianity (as a religion) appear? Why was it actually needed?

At the beginning, the apostles gave the teachings of Jesus Christ to the people, and the communities continued their lives, occasionally meeting to talk about God and / or to perform the Eucharist. And then the next historical information is that there were churches, and priests structured hierarchically with ranks like in armies and so on. So, when was the transition done from "people changing their lives according to the teachings of Jesus Christ" to full fledged religion with temples (churches) and priests? As far as I know Jesus: - came to fulfill the (existing) law, not to cancel it or its prophets (Matthew 5:17) - sent the apostles to teach - did not send anyone to administrate / organize anything (food, widows...) - did not command anyone to build any temple (church) - did never show any love towards priests and other "spiritual" leaders.