Who decided on "origin"?

origin: the source the code first sprang from

You connect a repository to GitHub with git remote add origin. But why "origin"?

When you git clone a repository, Git automatically names the source "origin", because that's where the code originally came from. A straightforward name for a straightforward concept.

What's interesting is that you can change it (git clone -o, or the clone.defaultRemoteName setting). Developers worldwide kept the default anyway, and "origin" became the shared word for your main remote. The software world is full of shared words that started as defaults. You'll discover many more as you go.