The list of ancestors now focuses on the descendants of Kohath. It gives more detail about two family lines:
Aaron, the son of Amram, and
Korah, the son of Izhar (6:23–24).
It then names one of Aaron’s sons, Eleazar (6:25). The main focus is Aaron’s line through Eleazar, who later received the high priesthood.
Aaron and Korah were cousins. This family connection helps explain why Aaron’s appointment as high priest caused strong resentment in Korah (see Numbers 16:1–3). Conflict within families is not new.
Korah and his sons may be mentioned in detail here because of Korah’s later rebellion. That event made his family line important in Israel’s history.