Of the list of UI libraries and frameworks you listed, only Polymer creates Web Components. All the others have their own component model.
There are Web Components libraries besides Polymer: Skate JS, Reactive Web Components, Bosonic, X-Tags, and probably others. They're all interoperable.
There are Web Components libraries besides Polymer: Skate JS, Reactive Web Components, Bosonic, X-Tags, and probably others. They're all interoperable.