Probably, but where would be the fun in that? ...................................................

Plants almost do it. If we could modify our biology such that we don't need to consume living material, but rather dead matter with energy potential like methane or something, or perhaps just absorb sunlight.

Another thing to consider is destroying neighbouring habitats by doing general things during our life. This can be taken to the level of bacteria in your armpit which you kill when you wash, bugs you crush when you walk, fish that choke on our waste materials.

It would be technically possible, but would require a ridiculous amount of effort, requiring an extreme adaptation to our lifestyle which would no longer be normal by any standard we have today, either by how we interact with our current environment or by putting ourselves in an isolated environment where we'd be incapable of affecting other life. It would also require aggressive bio-engineering to have people that aren't riddled with 'other' lifeforms (this would be 'ethically' difficult too, as it's not even easy to decide what is part of a human and what isn't). We'd also need to use a fundamentally different system for energy intake.

Whether you could consider the result human? No clue.