Why is the Metamorphosis considered universal?Please elaborate.

I would imagine that while no one has ever actually turned
into a bug and a rare few might have imagined they did, everyone has felt like Gregor at
some point in his or her life.  Gregor is a bug now, but he was acting like a bug and
was being treated like a bug long before his metamorphosis on page 1 of the novella. 
Gregor is an insignificant worker bug for his family.  He is unappreciated and
disregarded even though he is solely supporting the family financially.  Once be becomes
an actual bug, he is treated with all of the horror and disdain humans have for most
bugs.  The family is disgusted by him and does as little as possible to help him.  They
eventually just want him gone, just as most people will eventually call an exterminator
to get rid of pests, so this family feels.  It is the maid who ultimately gets rid of
his dead body -- the family is removed from the reality of Gregor in the end of the
story. Most people can relate, if only on a small level, to feeling unimportant,
insignificant, and a nuisance to those around them.  Gregor's wanting to please and
sense of self-sacrifice are also aspects of his personality that are universal.  It is
human nature for most everyone to want to live his best life and do the right things for
the right reasons.  People can see those admirable qualities in Gregor. The story is
universal on many thematic levels.