As the dictionary defines murder, taken at face value, you are correct. Only humans can be murdered.
So let me explain why I used that term 'murder'. If you believe, as I do that the human being is a living breathing animal (The human's phylum is Chordata (vertebrate). The human's class is mammalia. It's order is primate (the same as apes) then, you could say we belong to a certain group of mammals. We are just one of many in the group. So the example of shooting other living, breathing creatures purely for the fun and thrill of killing fits the basic description of murder. I use the term 'murder' as an analogy to describe senseless killing of an animal similar to killing the human animal. (Certainly you understood that.) Physiologically there is no difference. If I shot a deer in the heart and shot a human in the heart the reason for death is the same. We share lungs and brains and livers and other organs that function similarly. But senseless killing (murder) is exclusive only to elitist humans? I think you get the picture.
Someone who gets on an airplane and fly's all the way to Africa to go trophy hunting for big game is NOT hunting for food. They are hunting a trophy to brag about. Hunter of all types want the "big one". This is an example of 'unnatural selection' or 'human induced evolution'. There have been scientific studies that show the negative effects of unnatural selection. I'll post a link below if anyone cares to read it. Beware, it is written by scientists not hunters. (I can hear it now...prolly more of those dang liberals)
Again, I have no problem who hunt and harvest food with respect to nature. I despise those who 'kill for the thrill' and there are plenty out there.
For those that don't believe in evolution or science then don't bother reading we have nothing in common.