Regarding Hillel the elder. The Babylonian Talmud and parts of the Jerusalem Talmud seem to say that Hillel is a direct descendant of King David,from son to son, yet in other parts of the Jerusalem Talmud, it says that Hillel’s father was from the tribe of Benjamin, but on the mother’s side, a descendant of King David. Where and why did this discrepancy come from?

There are two contradicting sources in regard to the ancestry of Hillel HaZaken. In Yerushalmi (Kilaim 9:3, Ketubot 12:3) and Bereshit Raba (33:3) it states that his mother was from Yehuda while his father is from Binyamin. However the Bavli (Ktubot 62b) and the Midrash (Bereshit Raba 98:8) state that he is of paternal ancestry from King David. These two sources can't literally coexist and I don't know the real answer to reconcile the two. It appears that the Binyamin version is more accurate and the Yehuda one is a figurative one. Some hold that is was necessary to link him to King David for gaining authority to his lineage later in time; others, that when it says he was from the Davidic lineage it is to say that it's not from King Solomon's line.