A "religious" person like me usually does show compassion to dumb animals. However, we do not consider them to be human, nor do we generally anthropomorphize most things.
I am against any kind of cruelty, but also against the idea that dogs "cry" and chimps "think".
I have long been fascinated by crows and other wildlife and take a walk daily in the woods. I choose to live next to a 23,000 acre wildlife management area. This state land is specifically devoted to promoting the wildlife HUNTING AND FISHING opportunities present there.
Of course as a vegetarian, you may accept eating fish, as being Politically Correct (many do). Why should there be a categoric difference in fleshy life forms?
I remain open to any type of proof , but am entirely skeptical of hypotheses!
And besides, no man (or woman) can DEFINITIVELY state that plants feel no pain, they just assume so!
You are certainly entitled to reject modern scientific findings regarding animal intelligence, just as you are entitled to reject the modern scientific embrace of the theory of evolution. I am afraid, however, that your rejection puts you in the camp of obsolete scientific thinking.
Vegetarians by definition do not eat fish. I certainly do not. And, ethical vegetarianism has nothing to do with "P.C." It's a concept as old as Pythagoras, and probably older.
Modern science is unanimous in its conclusion that animals feel pain. As far as science now knows, plants do not feel pain. You may enjoy this essay explaining why:
http://skepdic.com/plants.html
Do plants experience something like pain? Perhaps. As you correctly point out, we will never know for sure. Is it on the level of awareness of a cow or human? Of course not. Since one must eat to live, it follows that if one wishes to cause the least amount of suffering, one should eat lowest on the evolutionary scale, that is, eat only plants.
I offer this message as a rebuttal, but I accept that you and I will not agree on whether or not nonhuman animals think and feel (my cats, I'm sure, disagree with you as well). Still, it is good that you reject cruelty to animals, for whatever reasons you may have. Having worked at a sanctuary for abused, tortured, and mutilated animals, I can tell you that their capacity to suffer is all too real.
There are some people who don't care at all about cruelty to animals, and some who outright enjoy inflicting it (such people are usually cruel to other people, too), and while I respect your opinions despite disagreeing with them, for those latter people, I have only comtempt.