That’s why I said “these horses”. I think horses have changed so much from being domesticated and bred for certain traits that they would look nothing like their ancestors who were here.Mostly true, technically the earliest direct ancestor to the modern horse evolved here in North America. That ancestor, Eohippus migrated to Asia and the last North American species Equus simplicidens died out around 10,000 years ago. There is a hypothesis that human hunters were a driving factor in the extinction to horses, and that the Spanish were actually doing a re-introduction.
None of this changes the fact that they were absent from the landscape for 10,000 years, the landscape changed without them and they are now a feral invasive that needs to be managed.