At least as far as the mythology is concerned, aren't humans and fal'Cie actually superior lifeforms to flora and fauna? In particular, humans were imbued with chaos.
That analogy also somewhat overlooks that humans have to use those other organisms to survive. I'll give you animals, if you would like, but if killing plants and single-celled organisms is morally reprehensible, you're really not giving them any option but suicide -- which would still be the taking of life.
Also, it's not really like the plants and one-cells are capable of having an existential conversation with the humans about their right to exist. They aren't sentient, nor do they have emotions -- though, again, I'll give you animals should you insist.
All life has the right to life, despite traits and characteristics. It's not for one to decide for the others; granted, there are times when life has to be taken or it seems there is not other choice (unfortunately.)
It's a food web, not a chain. Humans make great crunchy meals for some other lives, too (including other humans.) When dead, insects and one-celled organisms (hells, even during life with some small organisms) are living upon and inside the human body - both parasitic and symbiotic. Left to nature, the decomposed human will provide food for a new generation of plants. Provided undisturbed, life and death cycles well. Thing is, humans have done much to disrupt this cycle; and the disruption has more and more removed nature.
Actually, studies have shown that plants actually protect their young, themselves, and communicate with each other (and I'd not be surprised if with other lives sensitive enough to "hear" them, and considerate enough to listen.) It's all chemical, but it's still communication. Granted, they are not lives in the sense that humans will ever fully understand, but that doesn't make them "less than"s or "inferior". Yes, they can provide relief and cures for different ailments... I feel this doesn't have to include the undue butcher and murder.
To sum up, it's my belief that humans should be much more respectful towards others (humans and non-humans), lives that are ruthlessly tortured, butchered and murdered daily. I understand food, as I eat meat myself; but, why do humans have to torture them? Why can't we try to make the deaths as quick and as painless as possible? With all of our "progress" we can have more machines and techniques to take lives than to save them or to ease the last days (again, humans and non-humans). Why can't humans respect the lives that will perpetuate their own, who ultimately deserve the honor?
I'm on a soap box to some. I'm stepping off. My beliefs are my own, and for better or worse, I cannot enforce them. Still, I think I have a great point (but don't we all.) Basically it comes down to this: I didn't create these other lives, and no one else alive has either. Just because there are differences doesn't mean that I have the right to use and abuse any other life around me. Humans don't know everything about those lives, and we never will. Does that mean stop learning, no. It means stop being cruel, stop excusing evil for "progress" or "education." Accept we won't know some things, we won't be able to solve some things.
One last thing, medical research... I myself take medicine, and undoubtedly lives were lost testing that medicine. If not lost, they were tortured for it. I need those meds, and I don't know how to find answers without the use of such methods used against animals, plants, etc. I always wondered why don't they use chemicals and levels that the human body can take and different ages, but... Until someone decides to do that (and that would require human testing) - because I'm not a chemist (and feel that I'm not smart enough to be so). This is a truth, I'm not proud of it, but there is one thing I can do: honor those lives lost or harmed. I can pray for them, I can wish them a better afterlife, and I can love them for what they've done to and for me. This may sound stupid or primitive, but it's a thing that never should have left the human psyche, even when science permeated life; honor those who do so much for you, how is that wrong or stupid, even if for 'such a little and insignificant life'?
Yeah, maybe I'm nuts. I don't think I'm wrong, though.
To get onto the subject of XIII: I believe that all life has chaos, because all life goes back to chaos. Humanity in the XIII-universe were not created by that which created all other lives (granted Titan and other such fal'Cie do provide a counter argument to this, and I don't know how to defend against that.) Humans would have no chaos until given it. I do not feel that any life is less than, it's just the humans who believe such - and since we are human, we only see the human side of things. If chaos is that which gives the power to use magic, for instance, than it only proves fal'Cie and other non-human lives have choas, because some of them use magic (tortoises, behemoths, plant-like creatures, etc.) I said this before, though... here or on another XIII related thread. Humans were given divine gifts by Etro, fal'Cie were given divine gifts by Bhunivelze, while other lives were given divine gifts by whoever created them and/or the cycles of life.
Personal speculation: I'm really starting to think that perhaps Mwynn knew how to control the chaos, knew how to keep herself from fully being enveloped into the substance that all life comes from and returns to. I think she is who led Lindzei to create humans, and perhaps has led other events in the course of existence. Mwynn may mean "tenderness" - but that doesn't mean she can't have a mean streak, and want revenge against her son, or maybe even needs to be with her son, for some cosmic reason - despite Bhunivelze's apparent hatred of her. I mean, we are told Yeul resembles Etro who resembles Mwynn... (and now I just thought of that three figured statue in the village of the farseers.)
(I know some people don't like Vanille, but her voice actress (same with Fang's and Lightning's) is a complete and utter doll!) Presently, it's still in the box, which I plan to keep it there until either I die and it passes on, or I find a good dirt-free, controlled place to display it. Though since I have the autographed box, I probably should just keep it there. 
