According to the prevailing scientific understanding of the Big Bang theory, the early universe was indeed in a highly dense and hot state. However, it is important to clarify that the Big Bang theory does not claim that all the mass in the universe was condensed into a single solid unit. Rather, it suggests that the universe began as an extremely hot and dense singularity, often described as a "primordial atom" or a state of infinite density.
In the earliest moments of the universe, the laws of physics as we understand them today break down, and our current understanding cannot fully explain the conditions at that time. Therefore, the exact nature of the singularity is still a subject of ongoing scientific research.
However, as the universe expanded and cooled down following the initial singularity, a variety of physical processes occurred that led to the formation of matter and the structures we observe today. One crucial factor was the rapid expansion of space known as cosmic inflation, which allowed the universe to become much larger and more homogeneous.
In the early stages of the universe's expansion, matter was primarily in the form of subatomic particles and radiation, rather than the familiar atoms and stars we see today. It took a significant amount of time for the universe to cool down and for matter to come together under the influence of gravity, eventually leading to the formation of stars and galaxies.
So, to answer your question, the initial singularity of the Big Bang did not directly become a star because the process of star formation required the universe to evolve over a vast period of time, with various physical processes and the influence of gravity playing a crucial role in shaping the structure of the cosmos.