, although I would probably go with "level." That's because you're really just talking about one level, which various things may share. Level in the general, abstract sense, not really discrete particular levels.
Here we are talking about levels which are different, just as basement level and roof level are different, or janitor and CEO levels are different.
Well, they could be different, but not necessarily. It could be the same level, that's not clear. Like I said, I think you could look at it either way.
But, really, the main reason for the choice I said I would make is that this seems, to me, to involve "Level in the general, abstract sense, not really discrete particular levels." I see it as referring to a "level" in a non-literal sense. You might substitute the word "norm" for level here. I wouldn't say "norms" if that were the case, either. Others would, I guess. Either one can be seen as "right." I agreed with you about that.