תפקיד
A theme of the Parshiot of במדבר and נשא, is the idea of תפקיד. This refers to knowing what our purpose is in this world.
This is learned from the various jobs the three families of the Leviim were given in transporting the Mishkan. The family of קהת had the most important תפקיד, as they were charged with carrying the holy vessels of the Mishkan. This included the Holy Ark, the altars, the Menorah, and Shulchan.
The family of מררי had the task of carrying the pillars or the frame of the Mishkan. And the family of גרשון were in charge of the curtains and coverings of the Mishkan.
Each individual is expected to do some serious soul searching to figure out what his strengths are, and how he can best use them in serving Hashem and the Jewish people. This is not easy but this is something we will need to answer to when we reach 120. Each of us has special talents and abilities that we should see as gifts from G-d. We are to do our best to fulfill our specific תפקיד in this world.