Human life is worth more to us because we're humans. What's wrong or surprising about that? There are plenty of valid arguments for the humane treatment of animals, but don't sit there and pretend you value all animal life equally.
Don't deal in absolutes. They don't have to be equally valuable for both of them to be valuable.
> why do you think that human life is worth more than animal life
which was asking whether value(human life) > value(animal life), not whether value(animal life) = 0.
Your line of thought is the basis for most human atrocities ever committed; you see your own group (species, race, gender, class, nationality, etc.) as more valuable, so you dismiss their own interests in favour of your own.
The point is that many humans have evolved to or desire to becoming more compassionate and inclusive over time, and this, the species difference, is one more barrier to cross. Instead of arguing about what will happen or what will never happen, humans will always continue to look at improving things. That's why even though we still have wars after thousands of years of civilization, we still want those to reduce and stop, and take actions that will help. It will take time to manifest changes in different spheres of discrimination and oppression, but as a species this is an inherent quality that takes us all forward.