i mean sure they didn't have modern medicine, but they were generally in way better health than we are now and still had basic plant medicine.
washing off wounds and wrapping them in medicinal leaves does a lot, and there is archaeological evidence of individuals who were in extremely bad health and yet through care from their tribe they managed to survive for years in such a state.
This idea that hunter-gatherers lived lives of misery and were too dumb to try to prevent bad things is unfortunately very widespread, when the reality is that hunter-gatherers had it about as good as you can expect from living without modern technology.