I don't think there's a person whom I've known who hasn't claimed to have experienced imposter syndrome. It seems like everyone has this feeling when they're engaging in something they have don't have complete experience or confidence in. This is a normal way to feel, but some people are better at overcoming it than others. The people who don't seem like they experience imposter syndrome are either well settled into their roles or are simply good actors who can handle pressure. At some point or another, we decided that this state of being had something to do with being an "imposter" rather than being a human being lacking experience. Unless you outright lied about who you are, you're not an imposter.
This reminds me how everyone says they're an "introvert". Even the people I know who are party animals say they're introverts because they need time to "recharge". We throw around these terms like "imposter syndrome" and "introvert" because they make us feel better, even though they describe most people, in which case they're really not that useful. Sometimes you've just got to buck up and not waste time overthinking, descriptions of one's self being one form of that.