I would say they do have an element of “part of speech” embedded in them, from when they came from Chinese. Many of them do end up being used multiple ways, and so expressing the idea as a noun or a verb doesn’t really matter much. But some are definitely more limited in how they were formed.
For instance 臭 means “smell” in the sense of “a smell” or “a thing that is odorous” while 嗅 means “to smell” as in “to sense by olfactory organ.”
It would be wrong to describe 臭 as “the action your nose performs” or 嗅 as “an odor.” Though, I guess it becomes less impactful when they’d both be answered as “smell” in kanji questions on WK. I will try to think of another example that isn’t overlapping like that.
Still, that’s not to say that everyone should feel the need to be that strict in answering for something like WaniKani. I was merely addressing whether the kanji have something like an essence of part of speech embedded in them.