Why should we care if polar bears were all extinct?

Think this, we humans are not the owner of the world. We just think we are. We have more power over everything well that's what we think anyway. Its the same for animals they think they own the world but they don't. Know one owns the world, basically all I'm saying is a polar bear is like a human? So as is every other living thing. We cant just say were the most important thing on this earth!