Is there sufficient evidence that human cells are not intelligent?
You seem to be asking if single mammalian cells are capable of intelligence. Yet, in your introduction, you mention that within a cell there are these seven characteristics that are fundamental in defining life. Then, you target more of your supporting quotations and interjections toward the definition of life. Of course cells are alive. You are alive, and so are the bacteria on your skin. Your title question is: 


  Is there sufficient evidence that human cells are not intelligent?


You have strayed from your question in your line of reasoning. Let's get back to answering the title question.

Is there sufficient evidence that human cells are not intelligent? The definition of "intelligence" is controversial, but let's look at Wikipedia:


  Intelligence has been defined in many different ways including, but not limited to, abstract thought, understanding, self-awareness, communication, reasoning, learning, having emotional knowledge, retaining, planning, and problem solving.


Human (or any mammalian, fungal or bacterial) cells are able to communicate, and solve problems, but most likely lack abstract thought, understanding, self-awareness, reasoning,  and emotion. Retaining and planning are somewhat more difficult.  Cells are able to retain information about a state of "being" and transmit that to progeny, a recent phenomenon known as epigenetics. Does this qualify as retaining and planning? I don't know. Cells also change based on environmental pressures through stochastic processes (a process known as evolution). Does this qualify as learning? Probably not, since the changes are usually pre-existing. The human equivalent would be finding out that you can swim by falling into water and not drowning. Did the person "learn" how to swim, or did they already possess an aptitude for it?