That's the machine learning 101 worldview. Initial level nodes are likely just minor inscrutable transformations. Later layers will be coding for features that,

That's the machine learning 101 worldview. Initial level nodes are likely just minor inscrutable transformations. Later layers will be coding for features that, at least to some degree if it's a tractable problem, humans can understand and agree with as useful features. They'll be fuzzy and not as clearly defined as a human would frame the problem, but their purpose can be explored and generally identified. In any case, speaking of them as representing singular features for simplification is appropriate. Maybe it's not one node that codes for legs, but two nodes that codes for legs like this and legs like that, but that's not relevant to the point.