To answer your first question, yes I am aware about the average life expectancy when SS was established. I'm not sure what you're getting at with that nugget of information or how you think it rebuts anything I said. I am also aware that there was not and is not any sort of means testing for SS. Again, I'm not sure what you are getting at.
As far as how SS equates to an anti-poverty program for the elderly, read the following quote from FDR and pay particular attention to the bolded section.
"We can never insure one-hundred percent of the population against one-hundred percent of the hazards and vicissitudes of life. But we have tried to frame a law which will give some measure of protection to the average citizen and to his family against the loss of a job and against poverty-ridden old age. This law, too, represents a cornerstone in a structure which is being built, but is by no means complete.... It is...a law that will take care of human needs and at the same time provide for the United States an economic structure of vastly greater soundness."
-- Franklin D. Roosevelt, August 14, 1935
The point I was attempting to make is that given that when SS was enacted individuals would begin to receive benefits at 62 and expect to only collect for three years before they would die, wouldn't the legislation have allowed a little more time between the beginning payment date and the date the of death if the purpose of the legislation is to ensure that the individual did not live old age in poverty?