Last month I researched two historical questions. I originally posted summaries on Twitter and am reproducing both here.1
Why Vim Uses hjkl Question: Why does Vim use hjkl and not the arrow keys for navigation?
Common Explanation: It keeps your fingers on the home row.
Historical Explanation: Bill Joy developed vi on the ADM-3A, which didn’t have dedicated arrow keys. If you look at the ADM keyboard, it put the arrow keys on the hjkl keys.