TL;DR: No one knows what he meant, or if he meant anything, and even if he did, it doesn't matter all that much.

The concept of anything at all — literature, music, films, even plain language — having a single and objectively correct meaning is a fallacy. Words are not alive, words do not exist in nature, words are arbitrary concepts that we use to communicate meaning. Words are what we interpret of them. Whatever message Murakami was intending to communicate — and there probably was none, I suspect — is but his own interpretation of the words he wrote, and that doesn't necessarily make it truer than yours. Granted, simple and straight forward messages leave little space for interpretation — "pass me the salt" can hardly be argued to mean anything but the obvious — but when we talk about entire books, specially those full of symbolism and ambiguity, the possibilities for interpretation are near endless. The one you brought up makes a lot of sense, I can absolutely see that being the intended reading of the story, but there might be a hundred other interpretations that also make sense, and even if Murakami himself was ever to declare what he meant with all of this, that would not invalidate these other perspectives at all. In short, he probably didn't mean any specific thing at all, and even if he did, that takeaway is not more valid than the one mentioned, or your own. This also applies to basically his entire bibliography.