1 Chronicles 9:2
Now the first inhabitants that dwelt in their possessions in their cities were, the Israelites, the priests, Levites, and the Nethinims. Now the first inhabitants that dwelt in their possessions in their cities were, the Israelites, the priests, Levites, and the Nethinims.
The first to dwell again in their own possessions in their own cities were the Israelites, the priests, the Levites, and the Nethinims. This naming belongs to the restoration after the exile, when records of descent established who could occupy the land and who could serve in the temple. It stands in the opening chapters of Chronicles, which give lists of names and genealogies and give special attention to Judah and to the priesthood.
The wider setting of 1 Chronicles 9:1-32 sets out the order of service reestablished after the return from Babylon as it had originally been ordained by David and Samuel. That setting supplies the mention of the Sabbath in First Chronicles, which points back to the events of David's life. The record preserves the names and continuity of God's people and the integrity of the tribes of Israel.
The genealogical records show that God is particular and keeps a faithful record of every soul in heaven. The careful keeping of the genealogy of Judah matters because Christ came through Judah. The lines of Judah and Levi remained unbroken until Christ's first advent, Judah's line tracing Jesus through David and the Aaronic priesthood continuing until it was superseded by Christ's priesthood.