Well in addition to food stamps, opebo, we have unemployment insurance and medicaid that come to mind.
Unemployment insurance doesn't cover most poor workers. (no one I knew ever got unemployment benefits, as the employer simply denied them - as you know if one is 'fired for cause' one gets no benefits, and since a lot of payouts impact negatively on the employer, they simply don't allow anyone to get it).
There is also Section 8 housing, which subsidizes housing costs.
That's only for families, and even they often have a very difficult time getting it (long waits, etc.)
One can make the case that this is all inadequate perhaps, but one cannot make the case that there is no safety net at all.
I think 3 months of food stamps is close enough to zero that we can say 'there is
no social safety net for single childless people'.