There are different kind of watch chains. A sport chain is really short, a Waldemar is really long. This one looks like a vest chain. Many longer chains like vest and Waldemars have fobs, and that's the purpose of the extra jump rings. The fob is a decorative dangle. They are sometimes tassels, sometimes have rockhound type gems like carnelian or bloodstone, or it could have some kind of engraved piece, etc.
The swivel hooks to the bow of the pocket watch, and the toggle would go in a vest buttonhole, then the fob would dangle down as an eye catcher. The chain would then be a snazzy accent to a well-dressed man as it ran across his vest. Many vests of the day had watch pockets, or the chain could extend all the way to a pants pocket.
In the days before a man could flaunt his wealth with an expensive, upscale car, a striking pocket watch was a way a man could show that he was successful.
