I like to write. Whilst I'm not professional, I spend a lot of time writing. Most of it doesn't get put anywhere public, but some bits do. I usually get a decent reaction, particularly to my travel writing. I've written a few political articles that have gone properly viral, and do a fair bit of public speaking/lecturing on a few different subjects. I'm generally considered to be a decent enough writer.
And I know nothing of grammar rules, or different sorts of words.
I don't know what a verb is, or an adjective, or those other fiddly ones. I have to spell check nearly everything because I don't know how most words are spelled. I put every facebook post into Word just to be sure.
I simply enjoy the creative element of putting words next to each other to see the effect they have on each other. No word exists in an immaculate vacuum of grammatical perfection. They all bend and shimmer in reaction to the words around them. If you told me what the different sorts of words were I'd immediately forget. I just don't think of them that way. Nor would it be useful for me to know! I literally don't know any grammar rules, other than perhaps instinctively.
What people forget is that these rules were put together later as a framework to explain what people were already doing with language. The language existed first. You don't need to know a single rule to be able to use it effectively and creatively.
I'd go further - the 'rules' of language were invented/discovered by analytical people, so that they could begin to understand the workings of a creative mind. Examining on the basis of these rules is to force creatives to think like an analytical person, which they may or may not be. It doesn't help them use the language better, and gives an entirely false impression of their creative ability.
Basically, when it comes to creative writing, I have no idea what I'm doing, it's simply what feels right. I can't analyse it at all. Words just fall out and get moved around till I like the feel of them. It's often far more fun to use the 'wrong' word and enjoy the metamorphic effects on the rest of the sentence.
I would fail any test that asked me even the most basic questions about language. Yet I write most days, and increasingly find myself asked to contribute pieces for all manner of outputs.
Surely the only valid test for any creative work, is the finished piece, be it a text, an album, a picture etc. Testing on the rules is putting the cart before the horse - it makes a potentially totally flawed assumption about how the creative character relates to their art.