Knowledge is what is gained through education and experience. Truth is what is found through education and experience. Wisdom is using what education and experience one has. And opinions are just that'; opinions.
Contextually speaking, you are correct. Sometimes, some things we learn do turn out to be incomplete or false. That is why we take everything we learn with a grain of sand, and continue our education. But, in my opinion, to say that we know that we know nothing is a falsity. Do you not 'know' your own name? Your own mother, your father? Do you not 'know' that you are using a computer and keyboard to type in and submit your thoughts, your statements? While it is true that neither you, nor I, nor anyone else can know everything there is to know, with every breath you take you are learning something. Therefore you know something. And to say that you know that you know nothing, is as degrading and belittling to yourself, as if your parents told you that you a worthless piece of ****, that you will never be worth anything, and that you are and will always be some kind of 'sinner' going to some kind of 'hell'. It is ignorant, insensitive, and cruel statements and phrases such as this that cause children to grow up insecure and without a positive sense of self. And when Socrates or Plato, whichever one it was that made that statement, I don't think that he meant that he knew 'nothing' in the literal sense. But rather, he was speaking figuratively, in that he did not, nor could he 'know everthing'. So cheer up and believe in yourself. And that you are not the most ignorant kid on the block!
To rip a phrase we used when I was in the Marine Corps: ATTA-BOY!! I agree with you, and therefore Nietzche, rhat there are limits to the extent of humanity, as we currently know it. But who can, with 100% accuracy predict the future? As no-one can do this, then there is no-one who can with 100% accuracy predict the future of mankind. I disagree with your reference to your name. It does not matter whether one uses their birth name, or changes their name. Either way it becomes an ultimate truth. It is nick-names or slanderous names that are irrevolent. An objective truth is subject to its subjectivity.