Just because it’s always been done or natural doesn’t make it a good idea. Plagues were pretty terrifying events throughout history until we became aware of how they spread. The advantage we have over our animal counterparts is our ability to learn from our mistakes and upgrade our culture to decrease the chance of causing unnatural deaths in our populations. You are right we definitely shouldn’t isolate as tribes. This should be on the individual level when being exposed to anyone you aren’t around daily. This doesn’t constitute a tribe. If someone carelessly takes part in the spread of a pathogen without attempting to prevent it from using their body to get to other human hosts who are perhaps more vulnerable, they are ethically responsible for the death of every individual that is infected and does not recover as a result of that carelessness.