What originally lit up the new universe?

Via space.com: ‘A densely packed star-forming galaxy is reproducing the events that brought light to the early universe. The nearby compact galaxy named J0921+4509, which is rapidly producing stars, has many of the characteristics that would have been required to light up the early universe. Located approximately 3 billion light-years from the Milky Way, the star-forming regions of the tightly bound galaxy are surrounded by dense clouds of gas. Holes in the gas allow radiation to leak out, mimicking events that would have broken through the darkness that followed the birth of the universe.’