The BEST explanation for why the public wasn't able to learn much more about the virus and how it works immediately after cases were identified is:
Doctors and researchers were still asking questions about the new virus.
This response highlights the fact that COVID-19 was a novel virus, and at the beginning of the pandemic, scientists were in the process of understanding its biology, transmission, and effects on the human body. The evolving nature of research and the need for more data to draw reliable conclusions meant that much of the information was still uncertain or incomplete early on.