old things, old friend, old times, former, ex-
舊 centers on things from the past: old objects, former times, or a person who was once close, like an old friend. The ex- sense applies this idea to roles or relationships that are no longer current.
舊 is the traditional form of 旧. It combines 雈 (an owl-like bird) with 臼 (mortar), but the historical reason for this combination is uncertain. The character was used early on to express 'old' or 'former', possibly through phonetic loan or extended meaning.
Picture an old mortar (臼) with a worn-out owl (雈) perched on top. Both are relics of the past, representing old things and former times.
For キュウ, imagine an old friend named Kyu who loves collecting antique mortars and owl figurines: Kyu -> キュウ, and his hobby is all about old things.