No, Backbone is a collection of things and closer to a framework rather than a library, like React.
Backbone has Models, Collections, a Router, History, Sync, View and Utilities.
In contrast, React is only the view part.
So, it would be closer to say that React is just the View part of Backbone, you need to bring in the rest yourself.
Backbone is an elegant library but I think its popularity and ecosystem were on a decline even before Walmart -- which was one of the biggest corporate contributors (e.g. Thorax [0]) -- did a complete overhaul in 2016 to React [1]
[0] https://github.com/walmartlabs/thorax
[1] https://medium.com/walmartlabs/publish-react-native-bundles-...