I am not the medical expert you guys are, but I seem to recall mother's milk passing some immunity (antibodies?) down to their babies.The "normal and natural" way people acquire immunity is genetic. The first part is probably inherited through our DNA, the rest is stored in our DNA.
There's nothing new about RNA vaccines, we just learned a new way of producing them.
It all seems pretty complex but what doesn't kill us may make us stronger, unless it makes us weaker.
JR