The German word for man is der Mann. Der Mensch is a human/person. And yes, in Yiddish it has strong positive connotations, which have carried over into the (American, at least) loanword.
yeah person is more accurate. I wonder what the etymology of Mensch is, Lohnwort from Latin, long evolved, like Muenze? Umlaut applied to a derivative of Mann with an i involved, also long enough evolved the spelling simplified?
I no longer have my German language dictionary(-ies) or Duden books nor access to such where I am, sadly.
It does not connote those extra attributes. It means someone with integrity and honor, who always does the right thing. A mensch is someone you can count on. It is a very high compliment to give someone. But I've definitely known some disagreeable mensches.
Worth noting that "the man" may instead mean police/government/etc, usually with negative connotations. So context may make this less appropriate as a synonym than "righteous dude" as mentioned above.