The descendants of Judah have been listed, up to the generation of David, more or less. Now the focus zooms in on the line of the kings. First, David’s sons are listed, arranged by their birthplace and their mothers. Bath-shua’s (that is, Bathsheba) sons are not listed in birth order, as Solomon is the second of her son’s mentioned in 2 Samuel (and the only one named). Her first died due to the judgement on David’s sin concerning her husband Uriah. Most of David’s children are not mentioned elsewhere, but the ones that are don’t have well-known stories for good reasons.
From here, brothers and sisters are not mentioned as the genealogy follows direct descent from Solomon to Josiah. After Josiah, the kingdom of Judah does not pass cleanly from father to son because of foreign influence, from both Egypt and Babylon. A king would be deposed and his brother set up in his place, or his uncle in some cases. Eventually Judah is fully conquered and the royal family is taken captive while Jeconiah (a.k.a. Jehoiachin in 2 Kings) was king. This genealogy establishes that Zerubbabel is in the line of David. This Zerubbabel was the leader of the exiles who returned to rebuild Jerusalem.
There seems to be some debate about whether the families listed in verses 21 to 24 are desendend from each other or are other Davidic families contemporary with Zerubbabel. The impetus for this view is an early date for the text, close to the time of Zerubbabel’s life. This seems too much like eisegesis to me, imposing a meaning onto the text, when what we want to be doing is exegesis, extracting meaning out of the text. This text lists the sons of a father, picks one of those sons and names his sons, over and over. I believe there is still enough time between the return of the exiles and the reconstruction of the temple and the proposed date of the compilation of Ezra-Nehemiah (they were originally one book) for the author of 1 Chronicles to know about 6 generations after Zerubbabel and also be Ezra himself. The Chronicler wasn’t necessarily Ezra either, but that is the tradition.
Your words are true forever.