How exactly are you defining "authentic human"? It sounds like you're defining it as someone who always does the right thing without exception, who of course doesn't exist, QED.
What point are you trying to make, actually? Your argument seems to be that "authentic humans," however that's defined, are not just rare but nonexistent, even if other quietly heroic people who fill the same role do exist. I'm not sure what end you're trying to reach here.
The key sentence in TFA is "In essence, they cannot be compelled to be what they are not.". That's a highly theoretical argument and I simply differ of opinion. In essence everybody can be compelled to be what they are not, all it takes is the right circumstances and your Saint will be a sinner and the other way around.
I'm far more interested in the interplay between people and their circumstances than I am in labeling a particular human as authentic or not, it smacks of a value judgment in a vacuum, whereas IRL there is no such thing.
What point are you trying to make, actually? Your argument seems to be that "authentic humans," however that's defined, are not just rare but nonexistent, even if other quietly heroic people who fill the same role do exist. I'm not sure what end you're trying to reach here.