For me, votes are personal ratings of content
I think of upvotes and downvotes on challenge questions as akin to Youtube's "I like this / I don't like" buttons on videos. Or, the ratings Netflix asks you to put after you watch a movie (but without the five-star scale). I understand this is a bit unusual for SE, but it comes from the fact that challenge questions are providing content, not asking for help.
My vote says whether I liked the content and thought it was good. This is totally subjective. Continuing the analogy, I might dislike a movie because I think it had a poorly written and contrived plot, but someone else might think the plot was great. Or, they might say that I'm missing the point, the movie wasn't about plot but about well-choreographed fight scenes. Or that I don't really "get" what the movie is about. Other times, I might just not like a movie but not really be able to put why into words -- the movie just didn't work for me.
But, if most people like a movie/puzzle, that's a sign it's good, and if most people dislike it, that's a sign it's poor. Again, this varies for any individual person, but people's opinions do correlate with each other. So, someone looking for a puzzle to solve can decide whether to take the leap and based in part on votes, just like user movie ratings can help someone pick out what to watch.
A downvote does not mean that you think the puzzle doesn't belong on the site -- that's what close votes are for. Nor is it expressing disapproval of the user. Even Steven Spielberg put out some stinkers, but the users who criticized those movies aren't saying "You're not a director!" or "Your movies are not actually movies!" or "You should stop making movies!".
Whether you're making movies or puzzles, you shouldn't be afraid to experiment and try new things even if that means it might produce something people don't like. Not everything will turn out great, and not everything that turns out good will be liked by everyone. Making puzzles is hard. It's a learning experience for everyone. Dislike or criticism can be harsh, but try to treat it as feedback to learn from. Ideally, people would explain what they like or don't like, but even if they don't, don't take it personally and assume good faith.