There's a tendency for Westerners to view every religion through the lens of protestant Christianity. Religion is a notoriously hard to define concept (this was the running joke of a sociology of religion unit I took at university; each week we'd look to another attempt to define it.) The idea that it's all about 'belief', some confession of fact-statements, is very much from that protestant Christian understanding, a post-Enlightenment focus on words.

The boundaries between religion, culture, language, myth and storytelling, reflection.. these are all extremely porous and vary widely. It looks to me that the researchers in the article are aware of this.

Brent Nongbri's book "Before Religion" is excellent on all of this.

(Full disclosure, I'm an Anglican [Episcopalian in the US] priest)

There's a neurological argument that overgeneralizing cause from effect has survival benefits. There will be a high false alarm rate for tigers in moving grass, but that's a win if, sometimes, there really is a tiger. This leads to a tendency to assign causes for random events. That in turn leads to various belief systems not justified by the evidence.

Wikipedia has some notes in this area.[1]

[1] https://en.wikipedia.org/wiki/Neuroscience_of_religion