based on our current understanding of black hole formation, black holes are typically formed through the collapse of massive stars. When a massive star exhausts its nuclear fuel, it undergoes a gravitational collapse. If the star is massive enough and its core collapses beyond a certain point, it forms a black hole. This process is known as stellar collapse.
As for the central black hole in the universe, commonly referred to as the supermassive black hole, its exact formation mechanism is still a subject of active research and debate. It's generally believed that supermassive black holes are formed through a combination of processes, including the accretion of mass over long periods of time and the merging of smaller black holes.
Regarding your question about a star existing prior to the Big Bang, it's important to note that our current understanding of the Big Bang suggests that the universe, including space and time, originated from a singularity. The concept of time as we understand it may not have existed "prior" to the Big Bang. Therefore, the formation of a star before the Big Bang is not a concept supported by current scientific models.