The point is that we typically think of humans as "conscious" and "alive", but consciousness isn't physical; whether a human is conscious or a "ghost in the shell" makes no difference to the universe. In theory, a cell or ecosystem could also be "conscious", "sensing" and "thinking", since it also makes no difference. Furthermore, although its sensations and thoughts would be much different than any human's, they aren't completely unimaginable.

For example, an ecosystem reacts to changes, experiments, and adapts via evolution (and cells react to things and display some level of sentience). Thus, evolution can be considered a form of thinking: like how we form and execute ideas to survive and prosper, an ecosystem forms and creates species to increase the coverage of life over the planet.