I don't know what you mean by tuned in. I think they're alert and wary of us. They have to be in order to survive. Sometimes wild animals, through familiarity lose that wariness of specific individuals and can lose it towards humans altogether if they live were they're protected. That does depend on the species though.

We tend to anthropomorphize many animal behaviors. They react according to their instincts well apart from what we are, do or think.

Sometimes animals shipped off to slaughter seem to know what is going on.

Mammals, yes, to varying degrees depending on the species. Dogs are especially empathetic to human emotions. Reptiles and insects, no. Their brains are significantly less developed. You may have a pet snake you love dearly but it doesn't love you back. If you have a pet insect, it would eat you if it could.

I think they are aware of and react to us, as with anything else in their environment. There is a pair of Ospreys outside where I live who call out when I and the neighbors come out and swoop us to see what we're doing when we're out and about.

Of course. Everyone who lives with a furry roommate has probably experienced some sort of connection....and many people who love animals have had experiences with wild animals too. For example, I have random butterflies land on me as a regular occurrence when I hike --- I honestly think they all somehow know that I have a butterfly garden at home and "raise" monarchs at my BnB (for release into the wild). I also have had other wild animals --- raccoons, squirrels, rabbits --- come to me with no fear on many occasions.

They are in so far as they adapt to changing conditions or die/suffer negative effects. Something as simple as a yellow jacket reacts to human body language stinging if they feel threatened. If you simply stay still one will crawl over you peacefully act tense and jerky you get stung. Animals like various birds, small mammals and such adapt to gain food through raiding garbage cans etc. Observing human behavior they will even return to a human who feeds them on a schedule. Using human constructs to gain food, crack nuts etc.

I think animals can feel/sense certain things like mood. My dog always paws me when he knows I am down.

I would like to think so but I also tend to anthropomorphize animals having a vivid imagination.

All energy is connected. Even humans are tuned into all nature, although most westerners are trained to ignore it.

Definitely yes, there were some fascinating experiments done with a McCaw parrot a number of years ago.
The Bird had a very high vocabulary and was devoted to his owner with whom he had lived for many years.
When she was placed in a seperate room and shown various pictures, the parrots reactions and comments were recorded.
The Bird had a high sucess rate rate in making relevent comments regarding the pictures his mistress was looking at.
Such as when the owner was shown a picture of a man on the telephone, the parrot asked "what are you doing on the phone?"

here is some footage from the experiment, the actual interesting stuff starts at 4.30

In what regard? Like if they watch us from the woods when we're having a picnic with children laughing, do they know we are happy and not a threat to them? Many see us and flee so know that we are a threat to them. I guess what I am asking is what do you mean by tuned in? If you simply mean awareness then of course they are. That is how you get bitten by mosquitoes. Further some interactions with them are based on habit or repetition, that is why it is possible train some animals. Of course the lower the form of life the more their actions will simply be instinctual.