when it comes to the halacha, if i wish to reduce the Law to a single purpose (silly idea to do, but i can have a little monocausophilia as a treat) i find the racism hypothesis more convincing than the hygiene hypothesis partly because even the highlights of the hygiene hypothesis: the cut your cock/don’t eat strange meats/menstruators reee require less rationalisation if you see them as components of “you have to do them to be Different and Better”
yeah you can come up with some things like pork being slightly more dangerous than other meats in antiquity but have u ever looked at the big 613 mitzvot list — there’s more to it than just how to wash your penis and be a farmer, like there are lots of ways to run a temple with sacrifices and these are some very specific ways being commanded where the rationale turns out to be “don’t do what the heathen (also running functional agrarian societies) do”
the whole passover suite of commandments is so super-rational that it is marked out especially as requiring a booster dose of Meaning every year to keep it going including a story about the most epic time some foreigners all got wiped out and your people survived.
also the big book of moses itself says the reason for these laws is because they are Israel’s side of the covenant, the other side of which being Tetragrammaton’s promise for Israelite supremacy. ritual cleanliness is a part of this but considering it’s part of a big list including a hundred ways to say “idolaters reeeee” it is strange to ascribe it as The Cause.
of course it is strange to ascribe any one thing as The Cause because the law expands beyond any attempt at rationalisation.