Re: Oh the joys of "cloud"
Codespaces is not code repositories, its an environment for developing changes and running the stack of software you are developing in the cloud. Its an evolution of things like docker-compose to do "local" development, but running the containers you need (and the ones containing the code you are changing) remotely instead of locally.
It solves the problem of "I've just been put on this team, what do I have to do to start making changes to the code and testing it out" - with codespaces, you just start editing code in either a browser based editor, or in a local VS editor, and the changes are automatically run on instances spun up for your work. The idea is to speed up the time before a developer can start contributing, and reduce issues around different environments for different developers.