'He's a real mensch," people sometimes say admiringly of a good-hearted man, "a decent and responsible person" as a Random House dictionary puts it. This newspaper, in a recent article, defined mensch as "a man with a heart" and gave its origin as Yiddish.
But that's only part of the story. While mensch may have entered American English through Yiddish, the latter adopted it from German, where it has been in use since the Middle Ages.
In German, Mensch (a capitalized noun) means generic man, human being. In Martin Luther's translation of the Bible, God did not create man, but den Menschen, a gender-neutral being. And the rest of the Bible goes on to use mensch when speaking of man, woman, and child combined. ("What is der Mensch that thou art mindful of him?")
In English, for lack of an equivalent for mensch, you have to point out that it is humankind you are referring to, in order to avoid confusion and the appearance of sexism. In German, you simply use mensch, and everybody knows you are not just talking about men. Thanks to mensch, Genesis is not a sticking point for German feminists.
It could be, though, on a technicality, because der Mensch is a masculine noun. Is there a dent in its gender-neutrality after all?
Furthermore, in English, one never hears a woman referred to as mensch, while in German a woman can be called mensch, as in ein Heber Mensch, meaning "a dear person." So somewhere on its way from German to (modern-day?) Yiddish, the meaning of mensch was narrowed down to the male.
Funny what can happen to a word once it emigrates.