I find your formulation most attractive, but I still cling to the possibility that there existed a “soloist” sparrow already in the songs of Sappho, and that the “Achilles Painter,” who flourished in the fifth century BCE, alludes to such a “soloist” in one of his paintings, as I suggest at https://classical-inquiries.chs.harvard.edu/musings-about-a-scene-pictured-by-the-achilles-painter/ and at E§4 of https://classical-inquiries.chs.harvard.edu/a-scenario-for-exchanges-of-comments-on-a-planned-monograph-about-the-ancient-reception-of-sappho/.