The Bible talks about the born of messiah the evangelius shows the great event in the History of Human been.
According the Holy Writings the people in the painting are shepherds which the angels advise them to adorate the King.
I think that the artist intention was to highlight the power of the child which represent the light of the world.
Mary had the blessing to be the mother of the messiah she was chosen by God according the Lucas Book. For this reason she is a special Human been.
