The story of horses is more involved and imo more interesting than this.
In the standard model, horses evolved in America and spread to Eurasia. They then went extinct in America, at the same time as many other large animals, quite possibly due to overhunting by the ancestors of the American Indians.
If the ancestors of the Indians hadn't wiped out horses, the Indians might have had wheels, carts and cavalry when Europeans showed up, and given them a much harder fight.
There's a concept likely to make a PC-person's head explode!
However, to get back to whether horses are invasive. Let's assume horses evolved here and were wiped out by human action. (Yes, Virginian, Indians really are humans, not an exotic species of wildlife.)
Then Europeans showed up and returned horses to America.
How does that differ in concept, other than in timespan, from reintroducing wolves to Yellowstone? Except of course that it makes Indians "the bad guys," and white men "the good guys."
I don’t get this, we say that nature argues that sexuality between men and women entails heterosexual marriage. But we’ve obviously trodden all over that good.
If we should not care about the goods of natural creation, should we not equally care about the natural goods involved in human beings?
There are two ways to look at this. The first is from the point of view of rational ecological management, what I would call “conservative, results oriented management”.
A good example of this is Ducks, Unlimited. An organization of duck hunters, they thought there were too few ducks on the west coast, so sought to naturally produce more. They created a few wetlands, and made a few minor changes that were conducive to ducks.
And pretty soon there were so many ducks that natural controls, like disease, came into play to reduce their numbers.
The bottom line is that if there are too few plants or animals, to “make more”, breed a surplus to be released in the wild. While their attrition is high, they are generally healthier, with fewer parasites, and inject new life and strength into the wild population.
However, the other way to look at environmentalism is the “leftist way”, which does not result in positive change, but is instead designed to restrict humanity, and promote shortage.
The end result of leftist environmentalism is ecological catastrophe. For example, the communists wiping out Czechoslovakia’s grand and picturesque forests with industrial pollution; pollution so foul that it caused a drastic increase in birth defects in humans and animals. Entire rivers fouled with pollution, and thousands of square miles horribly contaminated with radioactive isotopes throughout their domain.
No matter what they promise, this is the disaster that leftists deliver. No matter how bright eyed and enthusiastic they are about “restoring nature”, their touch never heals, it only curses and kills.
If you want to imagine what the environment would look like with leftists in charge, look at Mordor, where the Dark Lord Sauron held sway. He must have been a Democrat.