Now why would we want to be someone else? Why pretending? It's fun, it's a show, but there must be some root cause. Don't know much about tribal dances and African or Polynesian masks, so my take is probably a Western one. We want to be someone else because:
a. We are unhappy being what we are ('If I were a rich man...')
b. We want to do something unaccepted by society
c. We make a living out of it
d. A combination of the above.
I believe religions and early states allowed masquerades as a safety valve for [oppressed] masses. 364 days you do what religion/society prescribes, 1 day you are free to live the dream you cannot fulfill in you daily life.
In fact, we do a little pretending or acting in many mundane situations. We are not behaving the same at work, with our spouses, with our children, with our friends...They all have a different image of us, even though we don't wear a real mask at these encounters, maybe just a virtual one. Our acting was best described by William Shakespeare in his immortal "