^Right. It's nonsense to say that any
information about the content of a story is a spoiler. A spoiler is something that spoils, i.e. ruins, the satisfaction of the reading/viewing experience, say, by giving away the ending or the big shocking twist on whose concealment the whole narrative depends. It doesn't ruin the story just to know what it's generally about and who's in it.
(Although I read that somebody did a study recently and found that, on the average, people who'd been spoiled on the endings of stories tended to enjoy them more
than people who hadn't been. Maybe because their overall comprehension of the story was better, or something.)