The study team used the JWST to detect specific elements in the older star population of Gz9p3. see: Speck of light glimpsed by Hubble is truly an enormous old galaxy, James Webb Space Telescope reveals | Space
These target elements included silicon, carbon and iron, the latter of which is the heaviest element that can be synthesized by stars. This means these stars, when they died in supernova explosions, would have enriched the early universe with metals. Much of this metal content would have gone on to become the building blocks of the next generation of stars. The start of a theory of everything.