What a simplistic view of lions. I agree that lions don't really have the capacity to domesticate a flock of sheep, but to suggest that they're mindless killing machines that would meaninglessly mass slaughter sheep the first chance they got is weird. They're complicated creatures with rich emotional lives, and I've personally seen them plenty of times pass up opportunities to kill because there was no point. Interestingly, there's also lots of youtube footage of lions and other big cats attempting to care for other animals (albeit typically ineptly).
https://en.wikipedia.org/wiki/Surplus_killing
A local rancher lost a number of sheep to a mountain lion that apparently enjoyed surplus killing. After the first spree, the cat was captured, collared, and relocated but it came back and took out 11 more sheep plus an alpaca, after which it was culled by the state. Big cats are certainly interesting creatures, but it would be foolish to assume a given cat would care for something, eat it, or kill it for sport. They are all possible outcomes, and depending upon one's perception of cat psychology is a good way to get Roy Horn'ed and end up in a wheelchair.
The Wikipedia page also has weak evidence for lions being involved in surplus killing. It has two footnotes. http://www.aimspress.com/article/10.3934/mbe.2018031 is a simulation, and the abstract (article is paywalled) of https://zslpublications.onlinelibrary.wiley.com/doi/abs/10.1... only mentions “foxes, spotted hyenas and other carnivores”, and hints it may only happen when prey is easily available (as with a fox in a hen house, I suppose)
I think neither article claims it happens regularly.
Humans are "biologically designed" to love other animals and care for them. Not in an Elmyra Duff kind of way, but in the way that has allowed us to tame and domesticate the wild ancestors of the animals we still live with. In the same way that our animals have a docile and calm nature that allows them to be domesticated, we have a caring and loving nature that allows us to domesticate them. We are not lions. A lion could not domesticate a flock of sheep. It would just fall on the sheep and slaughter them, on the first day. Without our love for animals, which is just as ingrained into us as our love of eating their flesh, we wouldn't be who we are today, our civilisation wouldn't be what it is today, our bodies and brains wouldn't be what they are today.
Those animals have given us so much, and they will continue to give us even more. The least we can do is to treat them with respect and ensure they have a dignified life and a dignified death.