I don’t think though, that for the goal of living a happy life, any harm is theoretically necessary.

Whose happiness are we talking about? Surely if one person’s happiness conflicts with someone or something that already exists, they can’t both have happiness and harmlessness. (Also, what are you considering harm? Just harm to people? What about animals? Plants? The planet as a whole?)

Modern human life is inherently very harmful to a wide range of things.