why did the chicken cross the road jokesWhat is funny about "Why did the chicken cross the road ?" jokes that there are so many versions of it?

I have read numerous versions of this jokes, but have not grasped the funny concept of it. Can some one explain?
Probably because there is no apparent reason for a chicken to actually set out to cross a road?
And what might lead a chicken to do something so unorthodox, there lies the humour?

I can understand why a sheep would cross a road. They do stuff like that all the time. A chicken shouldn't actually be near a road really.. But why not a giraffe? Why did the giraffe cross the road? Hmm a chicken is more believawhy did the chicken cross the road jokesble and I can imagine it doddling over.
There is so much potential for adventure when that chicken crosses the road..

I guess it's just something that caught on. Whats up with the knock knock jokes though? They aren't funny either. At least a chicken is funny to imagine.
you are the only person with enough sense to ask this question

thats the stupidest joke alive, the only version of it that made me chuckle was this one, "why did the chicken cross the road? cuz therwhy did the chicken cross the road jokese was a hooker on the otherside" other then that those jokes are beyond retarded.
Can I walk you through it(to get to the other side)?
I dont know when that joke started so maybe it was funny in its day. I think its one of those things that is funny to kids.
I guess that its so funny because humans make up such ridiculous reasons for the chicken trying to get across when it was really very simple.Humans make things and situations complicated , and a child will do it the only way they know how--simple.