Ehhh, when I explain jj to people I like to say that it is "a tool to edit git repos", and that "the repo is still a git repo" because people have so many misconceptions of how jj works. When they see how different jj's interface is from git, they think it's a whole new VCS and are worried that it will break compatibility with other git tools.

That said, I only do this to avoid overwhelming beginners, when actually learning/using jj it is definitely more useful to think of it as a different VCS.