Over the years the part of Mary has always been thought of as the lead roll, for me the narrator is actually the lead roll. Mary just needs to sit still and quietly hold a baby, the narrator has to learn lots of lines and tell the story
Exactly this ^^
Mary and Joseph are usually given to the more quiet, not very confident children. There are no lines. Basically Mary and Joseph enter the stage, with Mary holding Baby Jesus. They stand centre stage, the choir come forward and they all sing, "Away in a Manger". Then Mary and Joseph leave the stage. The choir gets ready to sing the next song.
Yet they are coveted roles by parents who would dearly love their child to have a "Lead" role. Very often Mary or Joseph will start crying and run off.
I think, sometimes, parents underestimate how scary it can be for any child, or adult, to stand on stage facing an audience. A shy, quiet, nervous child is not going to suddenly become confident if a teacher picks him to stand alone, centre stage a
to deliver lines or sing solo. In fact the opposite is more likely to happen. He will see a load of eyes on him and he will freeze.
The Christmas pudding, usually gets a line or two plus be part of a small group dance - but that's a "crap part". Strange 🤔
The sheep are usually funny roles in our Primary school Nativity. Hence the children, who can deliver humorous lines with good timing and confident speaking voices are chosen.
Angel Gabrielle has to have a clear, loud speaking voice, with good diction. The Angels, again, have no speaking parts. They enter the stage sing a song, with the choir and go off. One or two may have a line.
There is a part for all personality types in the Nativity. Teachers know the personalities of all the children in the class so are best placed to decide which child best fits each role. Better than a parent who has no idea of the different personalities in the class but thinks her pfb should get the 'lead' role - Whatever that may be 🤔