I do believe you're right, Gaye!
Hives, the medical condition, is treated as either singular or plural, and there is no corresponding word hive. The word seems to be unrelated to beehives, and is labelled by the Oxford as "origin unknown".
Divers, meaning various, sundry, several, is not even a noun, and certainly unrelated to those who dive. It's normally labelled as literary and/or archaic, but that's never been a barrier in the past. (The word was used quite frequently by Shakespeare.) In case anyone's wondering, diverse is a later word, derived from this sense of divers. Divers doesn't seem to have such a strong sense of items being different from one another - it can simply mean "several", as in: "Myself and divers gentlemen beside / Were there surprised and taken prisoners." (King Henry VI, Part 1)