That seems to be obviously true to me. The alternative would be that consciousness simply appears at some point out of literally nowhere because there would be no lower levels from which it emerges.
* pushes the problem one level down ("why are cells conscious?")
* adds the problem of explaining how consciousness of a person relates to consciousness of its cells.
What would this model help explain?
Cells consciousness would be a much, much simpler sort of consciousness, something any "object" that somehow is capable of searching for food and avoiding "danger" should possess.
Higher level things emerging from similar, but lower level things is not a mystery, it's something expected (like ant colonies).