There is no grammatical error in what neil armstrong said on the moon. Even if people think that what he said is not a grammatical "mistake", but a problem of semantic expression and semantic understanding. It has nothing to do with grammar!

He later stressed that what he said was "one small step for man, one giant step for mankind". But what people hear is "this is a small step for individuals, but it is a big step for mankind." Who can completely deny that this is not caused by signal transmission?