In Jewish tradition, the biblical figure who is the namesake of the priestly family represented by the first aliyah is Aaron.
Aaron, the older brother of Moses, is described in the Hebrew Bible as the first High Priest of the Israelites. His descendants form the kohanim, the hereditary priestly class. Because of that lineage, a kohen traditionally receives the first aliyah during a public Torah reading, including services connected with bar mitzvahs.
Moses was Aaron’s brother and Israel’s central prophet, but he was not the ancestor of the kohanim. David founded the royal dynasty associated with Judah, and Samuel was a prophet and judge. In modern Jewish practice, claims of priestly descent are maintained through family tradition, while communities differ over how strictly the honor is applied.