I agree that AFDC at its inception was politically innocuous because it was conceived as support for widows with children. It was also passed as an explicit part of the Social Security acts. Since it was not contributory, however, the extent to which it was understood then as a component of social insurance is not obvious to me.
I would define social insurance as a program with more-or-less explicit, earmarked, possibly mandatory "contributions," and beneifts which have some kind of stipulated relationship to contributions. AFDC may have been thought of as social insurance, but it was not social insurance.
When AFDC began to become controversial in the late 1950's and early 1960's, its divergence from Social Security in the public mind becomes more clear. Except for a few conservative academics, nobody breathed a word of doubt about Social Security until the 1980's.
Clearly social insurance can be screwed up in any number of ways, including in terms of gender or the value placed on child care or other work in the home. I keep harping on the distinction, however, because social insurance has great political strength, and I think it is important to exploit this strength, first to defend what we have, and second to extend the scope of non-market social protection.
Regards,
Max