How do words get their meanings?

[Obviously not a complete answer (from a doc I am writing):] No discussion of semantics can escape the central mystery of how words acquire their meanings and contexts. The narrative structures [of proto semantics] are simple by comparison and define roles for words independent of the native meanings. So let us acknowledge two kinds of word meaning: native meaning context and role within a narrative structure. For the sake of discussion, I assume words acquire their native meaning context through repeated use in a single role within multiple occurrences of a narrative structure in varying physical contexts. That single role is a word’s native role.

The “mystery” of word learning is why some parts of the context are perceived as constant and become associated with the word, while other parts are perceived as varying and become part of the expected narrative usages. For example to use the word “sun”, for me, creates a vague picture of an outdoors with a sky and a specific picture of a sun. The vague picture is waiting to be clarified.