… Not true. Most go back either to the beginning of time, or to the beginning of modernity. The Middle Ages were, to those with a mild acquaintance with them, centuries remarkably free of “common superstitions.” Unless, of course, you count faith in God as a superstition. But even if so, you should notice that it tends to preclude faith in a lot of other superstitions; and that the medieval mind, though not yet aware of many later scientific discoveries, was hard-boiled when it came to gnostic and “spiritualist” sludge.
Certainly, the literal belief in space aliens is new. And the myriad of Darwin superstitions, fronted as truths. How about “Cancer is a newly evolved species.” Of what, exactly? There’s hardly any point in asking. Just say the word “Darwin” And all doubt vanishes.