This is not a monster-girl anthology. The characters in “Welcome to the Zoo Bar” are not written as monster girls; it is a “funny animals” story with the characters drawn to look like women. The characters in “A Candle for the Grim Reaper” are not monster girls.
It's more clear when you know what Jingai mean. According to UrbanDictionary : "a new term introduced in Japanese manga, which refers to non-human creatures who usually involves in some sort of relationship with humans (especially love)." You can technically say that monster girls fit the description but that's not the meaning here.
@Oeconomist ah my bad. All the other times I encountered "jingai" it was in reference to monster girls. After looking into the word I found out that it's actually a broader descriptor that refers to any nonhuman.