The tooling on top is inconsistent and kind of messy though, and harder to explain than the internals. I recall hearing somewhere that the tooling we see today as the user tooling was really supposed to just be the tooling for messing with git directly, with the expectation that something would sit above and make it actually user-friendly. I don't remember where I recall this from though, so could be just a post-justification from my own brain to explain the situation :)

that's not true either. originally it was simple internally - it was mostly shell scripts! writing text files! - but now it has all sorts of complicated optimisations.

the "middle" is somewhat simple for CS people, though - a graph of commits, you can put labels on them, you can send and receive strict appends to the graph to another repository. both the stuff under and above that is quite complicated in practice, but the UI does continue to improve - e.g. editing a past commit message until the release last week was ... complicated.

Nah, I remember that time vividly, Github became a thing about a year or two after it was already very much taking the lead.

GitHub became GitHub because git was the winner. There were alternative hubs that supported bazaar and mercurial and whatnot, but git won because for most people, Linus and the kernel team being behind it was reason enough to trust it.

(and I say this as someone who liked hg more than git)