Please just give up and slink away; you came to this "fight" not just unarmed, but hobbled.
Oh come on you totally ignore everything else I said. The fact that it is a contraction of “you all” is clearly stated. You just can’t comprehend it.
By the way. Northerner’s generally say “You All” and many southerner’s from places like Texas say “Y’all”. But, only people who learned British English say “you lot”. And in the last case there are not many left in America. And that is just the way it is.