> Currently, my simplest definition is "any self-aware organism capable of predicting the future to some degree."
Frogs and certainly embryos are not self-aware.
> I think we are rapidly getting to the point where we will be able to sustain ourselves effectively with non-animal foods in a way that will be more nutritious, more sustainable, and more environmentally friendly.
Nothing more nutritious than animal foods. This is basic science and evolutionary truth. The only other alternative to fit your description is the environmentally ruinous vegan diet which is terrible for humans.
> I want humankind to prosper longterm and I think our most immediate challenge to that is our violence towards each other and towards our environment;
I want humankind to prosper as well. Look how virtuous, caring and good we both are. Aren't we great? The immediate danger is the messianic lunacy being spread by traditional media and social media.
> If the majority of us adopted a view that intelligent life at all levels should be protected
Sadly, I don't think you could convince those militant and violent vegans set on destroying as much intelligent plant life as possible. But maybe you, caring as you are, can single-handedly stop them.
https://www.pri.org/stories/2014-01-09/new-research-plant-in...
http://www.bbc.com/earth/story/20170109-plants-can-see-hear-...
If intelligent life must be protected then I guess we have to take dogs and cats from their owners since these animals require meat to be healthy ( for cats to live since they are obligate carnivores ). I don't know how you sleep at night knowing that trillions of animals are being killed and eaten by other animals every day.
Also, the most environmentally friendly diet is the hunter-gatherer diet, which you in your immense wisdom probably reject in support of mass agriculture - the worst thing for the environment.