Why is the woman at the well included in the Nativity crib? The answer is, she isn't. Where did you get the idea she is?
In my lifetime, the woman at the well, St. Lucina, has never been a part of the Nativity Scene.
There is Our Blessed Mother, St. Joseph, the Baby Jesus, the Three Wise Men, and a Shepherd Boy carrying a lamb around his neck. Also a few barn animals i.e. sheep, cow, donkey, etc.