[ksk]

What they're trying to figure out is how it spreads so quickly when other viruses of the same family do not. Also this is an RNA virus (like most viruses), and RNA is not a stable molecule, especially compared to DNA. The ability of the virus to attach to and invade cells is also not an absolute. Our adaptive immune system can and does recognize the virus as a threat. What you flippantly described as "not hard to understand" is actually very hard to understand for the domain experts actually working in this field..