"Cause" and "effect" are abstract labels assigned to detectable objects / circumstances (the latter purported to concern "real" things rather than concepts or name-tags which belong to such schemes). Like turning on a light switch (cause) superficially resulting in a bulb glowing (effect). But they're not absolute labels. The bulb is just as much a cause of other effects itself. Both the classification of "cause" and the classification of "effect" can be applied to the bulb, depending upon the practicality, perspective or needs of a person in sorting out how to explain something or just addressing the existence of the bulb. It's kind of akin to sometimes calling Margaret Wheeler a wife, a mother, a city treasurer, etc instead of Margaret Wheeler -- depending upon the labels of the word-game or system referring to her. A chain wouldn't seem an applicable metaphor if there was only one cause and one effect. So you mean a branching sequence discriminated into countless units called "causes and effects" or many things having those relational roles attributed to them. But then how would a human or its whole lifespan be breaking that sequence by likewise being so distinct and distinguishable? A human is an "effect" in terms of having an origin, but it's also a "cause" (nothing else on Earth ever planted landers and rovers on the planet Mars). Consciousness is ascribed so many different meanings by varying camps of ideas that there's surely one that tries to declare it the exclusive property of watery cell organizations (John Searle comes to mind with his "biological naturalism"). But similarly there will be another definition that could assign it to an electronic substrate (computer, robot, etc) of the future, if not already.