"Chúng tôi là con người."
Translation:We are human.
I find Vietnamese to be funny like that. Adding or removing key words may or may not make a huge difference in meaning.
In this case (and also my opinion), it's not redundant because "con ngườI" and "ngườI" are distinct words that are related but have different uses. Very much how "human" and "people" are related but have different meanings in English.
I never think classifiers to be redundant though. One could say "tôi có gà ở nhà" and you may understand them because you knew the context of the conversation. From the outside, it could either mean "I have chicken at home" or "I have chickens at home". In Vietnamese, it's just more natural to have classifiers anyway: "tôi có thịt gà ở nhà" versus "tôi có con gà ở nhà".
Sorry I tend to make long posts. I'm not a strong writer, but I try to do my best to make it digestible. Hope that helps!