Why should it? The environment is there for the benefit of humanity. When preserving it helps people, preserve it. When it doesn't, don't. It makes no sense to value ecological responsibility in itself divorced from human interests.
I am one of your fellow human being. What you describe is not a prioritization of my interests, so you are not necessarily speaking for your fellow humans. My interests, and those of countless others, are best served by an ecologically diverse and sustainable future.
My viewpoint is that those who are quick to trample on the weakest, including endangered animals, will likely find it easy to trample on the rights of the poor. It is not in my interest to support that potential future where might makes right. Both my interests and non-human interests can be served at the same time, with no conflicts if viewed in the long term.
I know you are trying to push the argument to the extreme. At a minimum we should consider non-human creatures. This is to our own benefit. We have shown repeatedly that we are doing harm to ourselves by destroying the environment. As of now we are part of an interconnected ecosystem and we need the other parts of it.