Johann Jahn notes that some ancients believed that the "gods were formerly men."
Johann Jahn, Jahn's Biblical Archaeology (Andover: Flagg and Gould, 1823), 511-12
III. Festivals were celebrated by the heathen in honor of their false deities; on which occasions sacrifices were offered, feasts were held, there were various sports and exercises; and solemn procession, in representation of their mythological history, proceeded through the streets. To the Mysteries which were celebrated on certain of these festivals, no one had access, but those who were initiated; and still it does not appear, that any more correct religious notions were taught in them, than on other occasions. On the contrary, Cicer9 DE NAT. DEORUM LIB I.42.) remarks, that they were occupied rather with an explication of the nature of things, than of the science of the gods; but he makes a further remark, however, in his Tusculan Questions, Bk. II. 1, that the doctrine prevailed in them, that the gods were formerly men.