Just to be clear on that, the phrase "Natural Selection" could be seen as metaphorical, yes; the phrase describes a real world phenomenon of Nature in metaphorical language. Nature doesn't actually do any selecting in the normal everyday sense of the word "select" which implies a conscious choice from available options. So if I say Natural Selection is a metaphor, that is a comment on language and its flexibility and ambiguity; it is not a comment on the nature of fundamental reality.
Yeah,...I have already discussed that.
The issue is not just about a word here and there. It is about the way in which the term Natural Selection is used as though it is a well defined process (like a quality control or manufacturing process, for example) through which complexity increases.
NS is a chance environmental influence. It could go one way or the other...and no direction or outcome can be defined in advance.
Genetic variation on the other hand, is where adaptations can happen. So, if Nature is Intelligent, and works through DNA, its effects can be seen in genetic variations which lead to emergent properties, further leading to complexity and human development.