Honestly, I don’t even know what you are asking. Are you insinuating that…not only I, as an individual, need be modest…but my MBTI must also be commonly understood to be humble as well before I am qualified to make an assessment in this regard?
To answer your question – No. ENFPs are often described as being ‘self-effacing’…but I’ve never seen ‘humble’ attributed to the type <--which makes sense as ‘humble’ is often synonymous with unassuming, meek, etc. As for me personally, I can definitely present with some self-righteousness in attitude when I’m stressed or feeling rejected/defeated/undervalued… and then other times I feel very free from even the slightest sense of bitterness or frustration that others are not the people I need them to be… and yes, feel very humbled by Life and the good people I encounter…
You do know though that ENFPs & INFPs share the exact same functions right? See I’m not really thinking much about how qualified I am to do this or that (and I actually think you may have misunderstood what that ‘excessively humble’ bit was referring to in the first place). I see what I see because we’re playing with the same deck of cards and I understand the game. I know what happens to Fi when it is on a mission to right a wrong. I know what happens when it goes ‘sour’. I know how it can become…when it is anticipating resistance…when it is experiencing resistance…it can become smug and condescending. I don’t know this because I'm adept at identifying humility in my environment…I know this because this is part of who I am.
I do not doubt what you see in OA. What I see, however, is OA flipping back and forth like I described in my own experience above…between self-righteousness and openness. I don’t need you to see it. I don’t necessarily need other Fi users to agree…and it is easily dismissed as a flat/blunt/so-last/excessively humble manner because it isn’t threatening to us really. But I want my INFJ friends to know that what they are picking-up on exists in reality.