Rashi explains that that hashem counted the Shvatim in the beginning of tha Parsha, so we could know that they are compared to stars.
Just as hashem calls each star by name and counts them as they leave, so too the Shvatim were called by name and counted after they died.
The Maharal notes that only the twelve Shvatim are mentioned in the Parsha. He explains that just as there are twelve Mazalos and each one has many stars, so too the Shvatim are compred to the Mazalos and every member of Klal Yisrael is a star in the eyes of Hashem.
He is our father, he loves us, and we are as important to him as stars!