I assume you believe that people (at least) have some moral worth such that they ought not be owned, whimsically destroyed, etc. I also assume you believe that stones (at least) have no moral worth and can be owned, whimsically destroyed, etc. without any immediate moral consequences. So 1) tell me where you think the line is (even if its a very fuzzy, circumstantial one)

What makes you think there's a line? I care more about killing (or torturing) a dog than a stone, but less so than a human. Pulling the wings off flies provokes a similar, if weaker, reaction. A continuum might complicate the math slightly, but ...