made this combining champion.gg stuff across champions, but it's casually cross confirmed w/ sources from other sites
its look varies depending on whether you focus on higher and lower tier champions (and there are a lot of ways to characterize that but each way mostly correlates w the other) but a lot of patterns are consistent
the weird drop in winrate w/ experience past 100 games (which is also found on similar graphs present on sites like lolking and league of graphs) is hard to account for, maybe a result of the substantially smaller sample size or something;
interestingly, this pattern actually disappears when i focus on the top half (by winrate) of champions in each role - it turns into a flattish line rather than a downward slope (never an incline);
either way, i would focus interpretation on the 1-50 and 51-100 bits
however i make the graph, a slight tiering seems to emerge between roles as far as practice benefits goes
adc being particularly hard seems the most consistent, with jungle/mid being particularly easy coming in second place, leaving top usually in the middle, etc
support dances between being really close to top or really close to adc as you see here
maybe seems to track my intuitions about "if you had to choose between having an experienced jungler, midlaner, support, adc or toplaner on your team - with the rest of your teammates being average to mediocre - which would you prefer?"
second idea is that it maybe tracks role difficulty, but i don't subjectively experience support as one of the more difficult roles or conversely adc as one of the easiest
the difference is like a percentage point so who really cares i didn't plan to type a lot about this i was gonna c/p the thing and go oh well
You can't step in the same river twice.