I read an already old paperback novel in about 1969. Most human life is destroyed by a virus, and it is the story of one of the survivors. I remember:
he survives because he had just been bitten by a rattlesnake and
as he finds other survivors his hammer becomes the symbol of authority. There is a late scene when only his young son or protégé is willing to pick up the hammer.
It may have been called something like 'The Green Earth', 'The Good Earth', titles which do not do well on a Google search. My impression at the time was that the author was not a regular sci fi writer, but I don't know for sure.