One can use the social genus concept of religion substantively or functionally in a way that is either universal or local. It can exist in most cultures without existing in all of them. There are people in the past and in the present who do not believe in supernatural beings and phenomena.
References
Schilbrack, K. (2022). The Concept of Religion. In E. N. Zalta (Ed.), The Stanford Encyclopedia of Philosophy (Summer 2022). Metaphysics Research Lab, Stanford University. https://plato.stanford.edu/archives/sum2022/entries/concept-religion/
It is sometimes assumed that to define religion as a social genus is to treat it as something universal, as something that appears in every human culture. It is true that some scholars have treated religion as pan-human.
However, a social genus can be both present in more than one culture without being present in all of them, and so one can define religion, either substantively or functionally, in ways that are not universal. As common as beliefs in disembodied spirits or cosmological orders have been in human history, for instance, there were people in the past and there are people in the present who have no views of an afterlife, supernatural beings, or explicit metaphysics.