In English, the term murder usually means something closer to "the intentional unjustified killing of a sapient* being."

If it's not intentional, it's not murder, it's an accident. If it is justified, then it isn't murder, it's e.g., self-defense. If the creature killed isn't sapient, then it isn't murder, but it might be animal cruelty.

Note that in order for it to be intentional, the killer must also meet some criteria for sapience, but that's not necessarily the same as being human. For example, in English translations of the Bible, Jesus refers to Satan as "a murderer from the beginning." (John 8:44)