Too MUCH medicine is being prescribed (that is the old profit motive, again). Vinegar, saline water and alcohol are perfectly good substitutes for control of most of the pathogens we encounter, and antibiotics should only be brought in when common practice of hygiene and sanitation have failed to stem the infection.
The human body has had, for eons, an almost uncanny ability to fight off practically every pathogen encountered. In the normal state of things, only a few of the bugs out there are pathogenic, and they are kept largely in check by making the environment not conducive to their continued expansion of numbers, like control of pH, or mineral content of the aqueous solution, or temperature, or simple scrubbing off at reasonably frequent intervals.
No, we were not able to fight off everything. There is a recent child mortality used to be 60% by age 18 and life expectancy was less than 45.