Rappenglück identified specific painted circles with specific star in the night sky, including the specific cave painting Collins cites as proof that Cygnus was known and venerated—the image of a bird on a stick, which appears in a grouping with a birdman and a bull. The eye of the bird on the stick, Rappenglück said, was the star Deneb, a prominent star now in the Cygnus constellation. However, Rappenglück does not state that the Paleolithic people identified this star (singular) with a complete constellation—the many stars of modern Cygnus were not depicted, unlike the more complete depiction of the Pleiades group in the same cave, for example. Instead, he suggests only one star from this grouping, Deneb, was depicted, along with Vega (as the eye in the abutting Bull drawing) and Altair (as the eye in the birdman drawing).
Rappenglück attributed no special meaning to Deneb’s appearance on the Lascaux cave wall. It was, he noted, one of the brightest stars in the sky. The complete “Ice Age star map,” as he identified it, was not necessarily a mystical catalogue for the ages (though he thinks it is) but rather a depiction of the brightest circumpolar stars—drawn from the whole sky, not just one constellation. In terms of sheer numbers, the Pleiades, being multiple in number, seem to have attracted more attention than the single star of Deneb, and Vega, housed in the largest drawing—the bull—is much more prominent than Deneb.
Needless to say, the selection of stars (except for the Pleiades) does not conform to the form of the constellations known from historical times (which Rappenglück specifically notes in his work), nor is it possible to prove that the image of the bird used in Lascaux has a direct connection to the avian form given to Cygnus more than 15,000 years later. (Indeed, birds are among the most common shapes for constellations worldwide—next to Cygnus is Aquila the eagle, for example. Birds live in the sky and are an appropriate image for sky-dwellers, and Rappenglück makes no claim of connection to the modern constellation.) None of the other constellation identifications, such as the bull (now in the constellation Lyra) or the birdman (now in the constellation Aquila) survive. As I previously noted, the seated, short-necked bird in profile on the Lascaux wall bears no resemblance to the spread-eagle avian form of either ancient or modern forms of the constellation.
Rappenglück’s analysis proves nothing more than that Paleolithic people observed the circumpolar stars of their era and drew them on Lascaux’s walls. This is no different than ancient people did at any time or any place, and it does not require the logical leap of assuming a continuity of belief—much less one focused on one set of stars not emphasized above any other—across tens of thousands of years. And since all people in all places have access to (more or less, depending on your exact location) the same stars, there is also no reason to posit imaginary connections between cultures based on a shared Paleolithic love of Cygnus.
I know of no myth, belief, or practice that can be traced back unbroken to Paleolithic times. No god or hero goes back much farther than the Bronze Age in direct testimony, and no further than 4500 BCE or so in scholarly reconstructions (the reconstructed Indo-European pantheon). It will take much more than a couple of pictures of birds to demonstrate a coherent continuity of belief across anywhere from twenty to thirty thousand years of history.