The OpenAPI components is designed for the centralization of the common elements used across APIs, providing a reusable components library of schema, parameters, security schemes, examples, and other components. Each component can then be easily referenced from across all the other path, method, operation, request bodies and responses that exist across an API.
Not every element of your API should be componentized, but whenever possible you should define the surface of your API as small reusable parts that can be applied across different resources. You can even create centralized OpenAPI which do not contain any paths and only have the components object for storing of objects.