anyone
In this poem, "anyone" is the name of a specific character who, in a very homogenous town, manages to stand out.
noone
"noone," out of all the people in town, is the only one to care for anyone. The town's children pick up on the fact that noone is in love with anyone. In fact, noone cares for anyone as much as she cares for herself; what anyone loves, noone loves. When anyone finally dies, noone is there to kiss him goodbye and is later buried next to him.
someone and everyone
The townspeople are known as someone and everyone. All across town, someone is marrying their everyone. someone lives out life with their everyone in very much the same way as every other someone lives their life with their everyone.
