All of the options you provided can be considered themes, as they reflect overarching ideas or messages present in literature or narratives. However, if you must choose one that is slightly less abstract or more specific, "Love and loss" could be seen as less of a complete thematic statement compared to the others, which express a more definitive viewpoint or moral lesson.
Therefore, the option that might be considered less thematic in a more traditional sense could be:
• Love and loss.