Salt is a natural preservative, and one that is readily plentiful for any society with access to salt water. Using salt to cure meats is something that dates back to pre-history as far as I know, much the same as smoking meat. For a society without refrigeration technology, salting is the simplest way to ensure meat will stay edible long enough to use the animal effectively.

Now, as for the 'taste' of salt on foods, I am not certain whether this is an indirect result of our penchant for curing foods, and thus developing a taste for salt culturally, or whether biologically humans have a natural taste for salt.