There's no such thing as introducing species where they don't belong. Ecosystem are dynamic, several other animals serve as vectors for transporting species from a place to another. There's no such thing as a long term static equilibria where godess gaia looks like a Jehova's witnesses book illustration. This is an incredibly cultish and misanthropic position.

This is absurd. Without human intervention, catastrophic boundary crossing by organisms is slow and rare. With humans, it happens at unsustainable scale. We all know what it looks like for an invasive species to dominate an ecosystem and crowd out existing niches, and that's what it means to introduce a species where it doesn't belong. Just because it can also happen without humans around doesn't mean what we're doing is no big deal.