Aliya Summary: The Torah begins to enumerate the names of the tribes and family groups. It is obvious that the intention here is not to review the whole of the (almost) nation, but rather to focus on Moshe and Aharon. Note that the Torah starts the list with Reuven and Shimon, and when it gets to Levi, there is much more detail. In this brief Aliya, the Torah is identifying many of the “main characters” of the rest of the Torah. The Torah is also giving us the ability to continue to draw the timeline of Jewish history, by giving us the ages at death of Levi (we already know the ages of the three previous generation, those of Avraham, Yitzchak, and Yaakov), his son Kehat, his son Amram. That brings us to Moshe and Aharon. We are also introduced to Korach and his sons and Aharon and his family.
Although the purpose of this partial genealogy was to identify Aharon and Moshe, the Torah began with Reuven and Shimon before it gets to Levi. A reason offered for this in one of the sources is that since Yaakov Avinu spoke critically of these three sons, the Torah here lists only them, to teach us that they were important tribes despite their progenitors’ “mistakes”.