It seems to impact everyone differently. I suspect those with milder symptoms either have more robust immune responses or contracted a weaker form of the virus.
I was sick with a terrible respiratory thing from about Oct 2019 to Feb 2020. Was convinced I had early Covid.
I was directly exposed several times in the summer of 2020 and spent lots of time in ER hot zones with my dying Father and never got sick.
Hubby brought the Rona home from work Nov 2020. I tested positive and was mildly ill for about 3 days. No fever or cough, just a killer headache and fatigue, mild loss of taste/smell. We treated with Quercitin and zinc.
Now I wonder if I really did have it twice which could explain the mild case.