If moral principles are abstract possibilities that are beneficial to groups of living beings, then there are some moral principles that apply to human interactions but not to interactions between humans and nonhuman living beings or interactions among nonhuman living beings.
For example, the principle of nonaggression is universally applicable to all humans. If no human initiated aggressive action against any other human, this would be beneficial to all humans.
However, the same is not true among all living beings. If no living being initiated aggressive action against any other living being, ecosystems would collapse.