Why not have individual-level leaderboards for levels higher than 20?

I have personally only gotten to level 24 myself (and years ago), but I'm sure some of the better players could get way past that.

I would love to see other players' submissions and times.

What do you guys think? I have some times I would submit on level 21 and 22. They aren't GREAT times, but respectable. :)

Well, the good news for you is that the better players can't get very far past level 24 at all. The bad news for your proposal is that 21+ aren't actually interesting from an individual-level speedrun perspective: they're all identical to level 20 in every way, as far as I know. So I don't know the official rules, but probably the most sensible thing would be for the level 20 leaderboard to accept any 21-24 level times as submissions, too.

So it is that for the 20th level, applications from 21 and higher levels are accepted, because they have no differences from the 20th

Yeah, that's how seriousproducer had her Level 21 accepted under the "Level 20 Individual Levels Run".