If somebody says a thing and it means something to even one other person then it's a word, end of story,
True. Might not be an English word though
Take me to the wizened sage on a mountain top and show me the complete list of all valid words in the English language, let the God of All Words tell me the process for deciding what is and isn't a word. OH THATS RIGHT, NOTHING LIKE THAT EXISTS, LANGUAGE IS MADE IN REAL TIME BY THE PEOPLE WHO SPEAK IT
No, it's also made by everyone who ever spoken something in it. A language is not something that only exist in real time, it's also a story of everything that's every been said between the speakers of it, starting from before history and humanity itself. It's usually said that the eyes are the windows to the soul, and much in that manner the language is the windows to the soul of a people. In language is recorded everything they ever expressed, in it they have recorded their culture, the impressions they've gotten of other cultures, life changing events, memories of triumph and scars of disaster.
This is why neither prescriptivist nor descriptivist linguists are right and why sticking wholly to either side is foolish and quite simply narrowminded. Language is a book that is being constantly changing as it is written in in real-time, but that book was started a long time ago and the many, many years of authoring it has given rise to structures and systems that affect and sometimes even govern how people write in it today.