Additionally, started out life working-class and was working as a longshoreman while attending CUNY; Ta-Nehisi Coates spent some time describing Moynihan's remarkable gifts in an interesting article for The Atlantic a few years ago[0].
I avoided praising him too much in order to avoid other questions, but since you bring it up: We should also remember his advocacy of some bad things, including some arguably discriminatory or at least condescending policies toward his black fellow citizens, and support of mass murderers in Indonesia and East Timor. (I'm not going into details, but people interested in him should look up the whole picture.)