Value is a construct that is innate to humans alone, without that sort of discernment, nothing has an assigned value. Though it is worth recalling that animals are necessary, the premise is namely predicated on human existence. Just as some creatures can be harmful to certain environments in numbers too large to be sustainable, the same can and should be said of human beings in general.
Human value judgments allow us to pursue purpose and meaning, which are important and valuable ends. While animals may be said to have desires and objectives, there is no evidence that they ask questions or seek answers about the meaning or purpose of their existence.
As individuals we value what is close to us, what we care about personally. The majority of people will always consider certain animal's lives more important than the majority of human lives, as the animals in question are close to them and there are too many humans to care for all of them as individuals.