"Herd immunity" is a poorly phrased characterization. Epidemiologists use the concept by other names in non-human pathosystems. When a pathogen is confronted by a host population that varies in inherent resistance and susceptibility, the rate of disease spread among susceptible individuals is slowed with the increase of the proportion of resistant individuals in the population. It's a function of probabilities.

It's a useful concept, but fucked up in the case of covid since it's rarely a fatal disease, infection increases immunity (resistance) of individuals, and multiple clot shots seem to increase susceptibility of individuals.

TLDR - herd immunity is a numbers game of protecting susceptibles by surrounding them with resistant individuals. Useful idiots hijacked the term to gain political power.