I'm pretty sure that most religions in the old days (With the exception of Hindu's, Jan's, and Quakers) Did not believe in or teach kindness towards animals. I'm glad that the modern world and it's loving kindness has started a change (At least in Christianity) towards animals and their rights as creatures of God.
Animals have as many rights at you have: none.
The sentimentalizing of animals is what you are referring to as "kindness". And we'll get to how "kind" we truly treat animals in a second.
What people who rely on animals for work and food abuse them? None if they are realistic.
However, today we have a whole industry that delivers your animals right to you which tortures them from birth till death, so you that you can have your meat cheaply and frequently.
Without a doubt I will say that more animals suffer at the hands of man in our world than ever before due to the meat and dairy industry.
You can enjoy bambi all you want and indulge in the decadent act of owning a "pet" that you attribute human qualities to, but you live in a world where animals suffer incredibly all around you.
See, I grew up killing animals myself to eat and keeping others to use for food. We treated them "well", like animals. We didn't ascribe to them human attributes. We cared for their health and they flourished.
The chickens didn't know of any cage.
The rabbits' hutch was generous in size.
The deer lived as it would until killed usually within an instant, if not minutes there after. (As did any animal that we harvested.)
The cattle we purchased from our neighbors were not huddled and crammed together and force fed grains and antibiotics.
And we sure didn't keep "pets". Our dogs were well trained to serve their job and were fun to play with. None were on psych meds. Would have darted off to chase another dog. Etc.
The cats lived about to serve a purpose.
Sorry, but your "modern" world has basically created a life misery for most of the animals that hit your plate or their eggs you eat, or their milk you drink.