This list of Levi's descendants focuses on Aaron and Moses. It shows four generations from Levi to Aaron and Moses (compare Genesis 15:16). The Israelites lived in Egypt for 430 years (see Exodus 12:40–41; Genesis 15:13). So, this list of ancestors does not include many generations.
Genesis 46:11 lists Gershon, Kohath, and Merari. They are Levi's sons who moved to Egypt with their father and Jacob's family. Amram's wife, Jochebed, gave birth to his sons (Exodus 6:20).
The language is clear, so it is likely there are generations not listed between Amram and Aaron and Moses. This suggests the missing generations were between Kohath (Levi's son) and Amram (father of Aaron and Moses).