...is historical narrative that likely served as a focal point for the returning exiles. It perhaps served the function of a "manifesto" intended to inspire devotion.
Another noted issue: 2 Kings 24:8 which states the regnal length as three months, whereas 2 Chr 36:9 states three months and ten days. The author(s) of Kings, from the reign of Rehoboam on through Zedekiah (at the end of 2 Kings), presents regnal lengths in round figures. For those whose regnal length was more than twelve months, and exact year figure was given. So, if I reigned 17 months as King of Judah, Kings would either say my reign was one year or two years, rounding off the months figure. For those whose regnal length was less than twelve months (Zechariah, Shallum, Jehoahaz, and Jehoiachin), the author lists their reigns in exact months. The only special case here is Zimri, whose regnal length was a scant 7 days. But the internal testimony of Kings is that round figures are being used. 2 Kings used round numbers, the Chronicler used an exact count here.