Hoping not to offend. Not my intention!

I’m confused why Covid has killed so many people but others it’s just like a cold. I know people say underlying conditions and age can make it worse but then again it killed normally healthy people too. I am recovering from my second bout with Covid right now. First time it was a mild sore throat and fatigue. This second time it was a stuffy nose and headache for a couple of days. My husband had flu like symptoms both times. But he had a healthy coworker (military!) young, dad of 4, who died suddenly from Covid. So… why is that? How does it pick and choose? I’ve tried looking this up and there doesn’t seem to be an answer. Could it be genetic?