The immune system is an incredible marvel of engineering, protecting you against an infinite number of attack vectors without any online database update after initial installation. It develops countermeasures on the fly, deploys layers of Defense that coordinate intelligently as a swarm, and keeps track of which molecules belong to „you“ while those molecules keep replacing themselves with those obtained from the outside. It constantly ingests signals from billions of sensors over your body which function as first-responder Defense measures as well as repair kits AND evidence capsules for the cavalry that rolls in later. And that’s just a sliver of all the ingenious ways the immune system works.
I wholeheartedly recommend reading „Immune“ by Phillip Dettmer: https://www.amazon.de/dp/0593241312