violence of nursery rhymes

WHY do we actually sing nursery rhymes to children? is it our method of comforting them to sleep? or is it jus something we do because it has been passed down generations after generations? but watever the reason, has anyone ever wondered, how much violence there actually are in nursery ryhmes?.. (and they say we're having too much violence and gore in our movies and TVs nowadays)

first, let's start off with HUMPTY DUMPTY..
humpty dumpty sat on a wall,
humpty dumpty has a great fall,
all the king's horses and all the king's men,
couldn't put humpty dumpty together again..

er, can someone tell me wat comfort or good moral lessons are we or the younger generations suppose to learn from humpty dumpty? because apparently, i dun see any..

secondly, we have LONDON BRIDGE..
london bridge is falling down,
falling down, falling down,
london bridge is falling down, my fair lady..

when london bridge is falling down, it was suppose to be a tragedy.. so where the HECK did my fair lady come from? was it dat the writer wanted to warn a fair lady nearby dat the bridge is collapsin? i think NOT! i think the write had a sick mind to look at fair ladies nearby when a tragedy is happening right before his eyes..

next, we have ROCK-A-BYE BABY..
Rock-a-bye baby, on the tree top,
When the wind blows, the cradle will rock,
When the bough breaks, the cradle will fall,
And down will come baby, cradle and all.

i would understand why, if babies started crying after listening to this nursery rhyme.. the only thing i can say is, God bless their little souls and hope they don't live in trauma and worry that the cradle supporting them from below would one day break and give way to the ground..

then, we have JACK AND JILL..
Jack and Jill went up the hill,
To fetch a pail of water;
Jack fell down and broke his crown,
And Jill came tumbling after.

well, it doesn't sound as violent as rock-a-bye baby but it isn't pleasing to the ears either..

and last but not least, (well, there are plenty more, but i decided to stop at five), there's THERE WAS AN OLD WOMAN WHO LIVED IN A SHOE..
There was an old woman who lived in a shoe,
She had so many children she didn't know what to do.
She gave them some broth, without any bread,
and whipped them all soundly and sent them to bed.

gosh, gave them some broth, w/o any bread and whipped them soundly to bed? is that wat we want to instill in the minds of the little ones? that adults are bad examples and are violent?

in short, there are lots of erm, disturbing and violent nursery rhymes that shouldn't even have existed.. BUT not all are disturbing and violent.. for example: twinkle twinkle little star.. the most important thing for us to do, is to screen through the nursery rhymes and pick only the ones suitable for the little ones.. it is said that ppl learn best at a young age, esp before the age of five.. we wouldn't want them the learn the wrong things and to stick with it in the future, do we? btw, has anyone ever notice that ABC, baa baa black sheep and twinkle twinkle little star has the same tune? ('',)