Christmas ornaments have many origins, most of them Christian, mixing with the pagan tradition of bringing evergreen trees into homes during the deep winter.
The site angels.about.com describes the Paradise trees that people would decorate in the middle ages, “they hung fruit from tree branches to represent the world's fall that occurred when Adam and Eve sinned, and they hung wafers made from pastry on branches to represent Communion, which symbolizes how Jesus Christ's sacrificial death makes salvation possible for people in this fallen world.”
The site also mentions that the first time a tree was specifically decorated for Christmas was in 1510, celebrating Mary and the birth of Jesus by placing roses in a fir tree.
Soon after, many people used fruits, nuts and cookies, sometimes cut into shapes of angels, to decorate trees.
Not long after, metal smiths discovered they could hammer metal in thin sheets, thus tinsel also made its way onto the trees.
Around the 1800’s glassblowers began making glass ornaments, which were quite expensive until the Industrial Revolution made mass production possible.
Nowadays people have a good mix of ornaments, from expensive handcrafted ornaments to cheap plastic ones bought at the dollar store, and of course there must be room for the paper ornament little Timmy made in Kindergarten.