Your argument strongly depends on a narrow view of the word "natural". Could you explain why your definition of natural is useful in this context?
Suicide isn't new or specific to humans, so calling it "unnatural" seems unnecessarily silly to me.
Suicide isn't new or specific to humans, so calling it "unnatural" seems unnecessarily silly to me.
Self-destruction is found in non-humans, but mostly as a reaction to acute circumstances. I'm assume you are widening the scope of what is suicide to include these examples, but they seem different than relieve of existential suffering that is human suicide.