Adventure time is a weird show for me, because it started out as mostly non sequitur brand humor, and I mostly enjoyed it. But as they built more continuity and larger story arcs, I feel like the show lost something. It must have been the writing and tone, because I normally enjoy having continuity in tv shows.

You are correct that there are a couple... questionable parts. But I think adult humor of some fashion is hidden and sprinkled in most cartoons nowadays if you look for it, partially to just give the adults watching the show with their kids some laughs.

But last I saw of it, Adventure Time is, at the very least, nowhere near as bad as Steven Universe when it comes to introducing content and concepts that are NOT meant for children.