It isn’t really that hard to see a natural place for “basic” to be defined. The points where peoples lives go off a cliff for lack of something simple are clearly visible: becoming homeless and losing shelter from the elements/violent people, being denied access to life saving medical care, not getting enough calories/nutrients of food to live.

Basic resources are the fence at the edge of that slope which leads to death. That not everyone gets them no matter what is a failure of humanity.