Am I reducing the worth of a human being or are they? See, we have one group that claims that humans are no different, than say, your banana slug. Each has equal value.
What do you mean by value here? How is the usual concept of value applicable to living organisms at all? How is this not the fallacy of confusion of categories?
If we have equal value, then what makes the slug, a slug? Aren't we all made of matter? Or is there something transcendental at work in the lives of either us, the slug, or both?
How is your idea of value related to the definition of a particular organism? What makes a particular organism a slug is that it fits our agreed description of a slug: if it did not, we would call it something else.
One can, of course, tell us from slugs by simple inspection. Why do you need vague terms like "transcendental"?
You seem to be ignoring how matter is organized to make various objects and organisms, in order to sneak in the supernatural.