I think it would be interesting to see how the older runner/runs did the speedruns before

The only issue with that is obsolete runs. It can be hard to see older runs if they’ve mostly been obsoleted (unless the filter included obsolete runs but that might get cumbersome and large very fast).

Your best bet is to go to the WR history for a category, look at the oldest runs there and then go check them out. It won’t show every old run, but it should give a nice general trend as games discovered new tricks or routes.