why r ppl the way they r !

I never have understood why ppl act the way they do..y are they so complex..y can't they express themselves ..y is everyone so different from the other..y isn't everyone simple n plain...y did GOD make us all different.....some people are rude some r nice to u..some act strangely...sometimes u meet a person n feel as if u've known him or her since childhood...what is it that some people lack and some others have in abundance !..is it all abt vibes....do they really help in judging a person...can u rely on it....how do u decide who to keep as friend and who to keep as an acquaintance..y do v talk to people only because we need to maintain some kind of relationship so that he /she may be useful later on ?....y can't we like everyone and spread love unselfishly....y are people so closed in their minds....y can't we reach out to others.....y???????