You do realize vinegar (acid) is a human killer right? Too much water is a human killer, too much sun is a human killer. Science typically starts with a hypothesis and tests it. Starting with the hypothesis that roundup is dangerous for humans is logical because we already know it is not safe for other forms of life.
Vinegar is only dangerous if consumed above a safe level, same with the sun, water, etc. Which was the point you seemed to miss. Toxicity is determined not by how it interacts with plants, but the safe level for humans, which is different than plants. Your assumption that everything is automatically dangerous is not founded in anything close to science or even evidence at this point. Prove that it's dangerous, it's been the most common and least toxic herbicide for years. Wouldn't you expect more concrete evidence to turn up similar to smoking, black lung disease, mesthelioma, etc? There hasn't been a huge upsurge in cancer rates, in fact they've gone down since glyphosate has been used. There is literally no concrete evidence currently that this is dangerous to humans at concentrations currently used. Find proof then I'll believe you.