That’s not my understanding of the phrase. The complete quote from Carl Sagan is more explicit:
Our Sun is a second- or third-generation star. All of the rocky and metallic material we stand on, the iron in our blood, the calcium in our teeth, the carbon in our genes were produced billions of years ago in the interior of a red giant star. We are made of star-stuff.
That aside, the point you are making is, in my opinion, more revelatory than it seems. It is one of the most common patterns in the history of science to understand that what’s happening over there is the same as what’s happening here, or vice versa. Newton’s theory of gravity came from realizing that what pulled the planets on their trajectories was the same force as what pulled apples to the ground. Stars themselves were not immediately understood to be the same as our sun. And for a case of the opposite, helium was discovered as an element in the sun before it was found on Earth.
Oh, sure. That’s the whole point of this thread, after all.