I'm sure mute people don't have any emotions.
-_- So the idea of all of your "against things, other than humans, having emotions" is the idea to express itself?
But what you seem to be arguing right now is how creatures would still be the same without our help. And you used the rainforest as an example.
-_O Okay, then let me try it your way: Compare a (pure) feral dog to a domesticated dog.
A feral dog seems to only act out of instinct, if it ever shows any signs of feelings, it is only towards its pack (if it has one).
A domesticated dog however, may be able to act out of instinct, but it's not as sharp as a feral dog's (unless if they were trained)... a domesticated dog seems to react to human emotions, knowing when a person is sad, happy, or etc. If they don't react to it, that's the dog's own doing.
Feral dogs only seem to know survival.
Domesticated dogs don't need to worry about surviving.
What's that got to do with plants?
Well, you said rainforest.
Rainforests aren't affected by humans (besides them being cut down) because they aren't "raised" by us humans. Just like other creatures, plants are on a need of survival. Plants have self-defense mechanisms just the same as other creatures. The more the plant is in danger, the more likely it has some form of self-defense, or a high reproductive rate.
However, plants raised by humans, just like domesticated dogs, act differently from "wild" plants. They react to music as well as emotion in the room. Try bringing a plant into a really horribly-emotioned house and try taking care of it. Trust me, if it's not as great as it should be, it's dead.
These plants don't need to survive, they're well-taken care of. And henceforth, seems to have more time to interact with its surroundings without survival in its genes. It can very well react in a happy surrounding as well as a sad surrounding. It can react to music the same ways baby humans do.
If the word "emotion" doesn't cut it for you, then how about character?
Or do you seem to believe that no animal or creature other than humans have character?