here were nearly 50,000 people who left Babylon as part of the plan to rejuvenate Israel (Ezra 2:64 & 65). Their main objective was to go to Jerusalem to build another temple in the name of Jehovah. God's objectives were various. He wanted to gain the loyalty of His own people. He was also simply keeping His promises. And, there were preparations to be made for the coming of the Messiah.
It is apparent (from the books of Ezra, Nehemiah, Haggai and Zechariah) that the leader of the returning remnant was Zerubbabel. He became the governor of Judah. Now, before he could begin building a temple, Zerubbabel had some other matters to deal with. Obviously, the journey of 50,000 people over a span of 700 miles (or so) was not a minor undertaking. Additionally, there were problems with some of the Jews not being able to prove their lineage (Ezra 2:59 & 62). In fact, that problem was so significant that it ended up costing some of the priests their position and office.
Upon the arrival of the great caravan of Jews to Zion, a couple of other issues were immediately important. Appropriately, worship through the collection of freewill offerings on the holy ground of the holy city was immediately commenced (Ezra 2:68 & 69). And, of course, the people had to settle in and find a place to live (Ezra 2:70). Obviously, Zerubbabel would have been very busy. But, the mission was surely worth the effort. They were only a shadow of what they had been centuries earlier, but their faith was alive and God was still the same. It was a good time to be alive in Jerusalem.