Is brave a noun? I'm using the tests put on the pages, from your description of nouns, brave is included but when I click it as an answer it states it is wrong. Have I misunderstood?
Go to The Free Dictionary by Farlex online and type "brave" into the search box and search. Everything you need to know about the word "brave" is there, especially if you scroll down quite a bit. There you'll see that "brave" could be used as a noun.