What is significant about all the main characters in Romeo and Juliet?Shakespeare's Romeo and Juliet

One thing that is significant about most of the main
characters in Romeo and Juliet is that unlike the key characters in
other plays by William Shakespeare, they are rather fully developed and interesting
round characters, who display a wide range of emotions and various personality
traits. 

That Romeo and Juliet are human in
their personalities is obvious.  However, the portrayal of the priest, Friar Laurence is
certainly a deviation from the typical religious leader of a community.  For, Friar
Laurence has not lost touch with the secular world and the deviousness that exists in
it.  For, in his good intentions of uniting Romeo and Juliet in holy matrimony so that
they do not sin together, he also is involved in a circuitous plan to unite the
families with Juliet's apparent death. 

Similarly, the
foolish, prattling Nurse displays what seems an incongruous personality trait. When she
pragmatically advises Juliet to go ahead and marry Count Paris, the Nurse figures that
Romeo, now banished, will never return to Verona and can no longer be of any use to
Juliet.

The sanguine Benvolio, whose very name
characterizes him, breaks through what appears to be his stereotype by displaying even
more cholera than Mercutio at the beginning of Act III as he tells Mercutio that if he
meets the Capulets he will not escape a brawl: "For now these hot days is the mad blood
stirring"(3.1.4).  And, Mercutio pointedly remarks about this uncharacteristic heat in
the peace-loving Benvolio,

Thou art
like one of these fellows that, when he enters the confines of a tavern, claps me his
sword upon the table and says ‘God send me no need of thee!’ and by the operation of the
second cup draws him on the drawer, when indeed there is no
need.(3.1.8-10)

Another main character who displays much
humanity is  Prince Escalus, who after the opening brawl between the Capulets and
Montagues and having decreed that anyone who breaks the peace will do so under penalty
of death, rescinds this decree after Romeo slays Tybalt and banishes him
instead.

Of course, Lord and Lady Capulet move from being the doting
parents to becoming the demanding insensitive aristocrats who desire the propitious
marriage arrangement for their daughter.

Indeed, it is in
part because of these well-developed characters that the readers/audience of
Romeo and Juliet suspend any disbelief in the swift sequence of
events of the tragic plot of Shakespeare's poetic play.