How does anyone in creative writing understand grammar?

The rules are so complex and incredibly nuanced. I have English or Spanish speakers who lived their lives reading and writing English or Spanish, who have never studied the mechanics of grammar, but are still able to communicate incredibly well, because English and Spanish are both living languages and people can pick up grammar just by hearing and seeing it, because they are living languages. <br>To be able to write Germanic languages well I would have to memorize over 400 grammar rules, and there is no way I can do that. <br>People who speak in tongues may actually be bilingual because of the fact that they are picking up rules subliminally. <br>So many people understand grammar incredibly well, but I just never could.