I am a human being, and a Homo sapiens, and a man, and a "naked ape", and a person. These are ways of just saying the same thing with different words. That describes the species I am; what my DNA sequence would indicate to anyone checking it. To a large extent the information in those labels will also describe the conditions needed for my continued survival, which individuals I would be able to reproduce with (and what offspring would result), my size range, and in a general way, my appearance. It would also eliminate the possibility of me being a fish, even if I claimed to be one. Even if I spent a lot of time swimming. And, conversely, it provides a standard to compare others' claims. If a garden slug is claiming to be human in spite of all the evidence to the contrary, it is easy to see the claims are not true, using a variety of tests and observations. A claim doesn't make a thing true.
Libertarian-
I am also a libertarian, and an anarchist, and a sovereign individual, and a voluntaryist. These are also just ways of saying the exact same thing with different words. This description shows I value the rights and liberty of each individual. It shows I recognize I have no right to initiate force. It shows I have no room for double standards for those who reserve the authority to initiate force or theft/fraud on innocent individuals. If someone claims one of these descriptive labels, but does not fit the description, then it is simple to see the lie. If you promote a "government solution" to anything, or if you are a bomb-throwing destroyer of innocent bystanders or their property, you are NOT any of the above. You are an authoritarian thug even if you claim otherwise.