There are no values in “objects” themselves.
Worth is in fact a vector, a relation, a tension between the subject and the object.
This tension has various parametres in different circumstances.
Were I a horse, I’d probably value a horse (a mare even!) better than humans.
Were I a hungry horse, I’d probably value a human better, because he might be my master that provides for me.
Were I a non-misanthrope human, I’d probably value humans better.
Were I a king at bay, I’d probably value a horse better, and I’d even give up my throne just to get one.
Were I an alien looking for exotic species, I would notice there is an inflation of humans on earth and I’d probably consider horses more valuable since they’re more rare.
Were I a gelous alien hating all other forms of life in the univers, I’d probably think that both humans and horses are futile and try to destroy them.
There are no values in themselves. And if humans make the standards, they’ll always look precious to themselves.