Which isn't surprising, seeing as how Plant matter typically ends up in animals, and animals matter typically does not end up in plants.

You made me think for a minute. I guess it depends. You can make compost with animal parts and feed plants with it. Where it gets a bit hazy in our understanding is with the decay/digestion of matter.

The human has a gut where it can digest the plant/animal stuff.

Did you know plants have a gut too? But it isn't located inside the plant. Earth acts as the gut for all plants, converting proteins and molecules into nutrients for plants, just like your gut does for you.

Furthermore, Earth's gut is no more "owned" by plants than your gut is "owned" by you. I don't think we have the necessary science to understand the deepest concepts of ownership and consciousness. There are millions of cells in your gut working autonomously without your conscious say or help, they have their own consciousness and it is keeping you alive. So if you can see it that way, there's not much difference.

Fun side quest - minerals (rocks/metals) and even DMT is in both plants and animals.