Not an answer to parent comments, just wanted to emphasize that coming from "somewhere else" <=/=> invasive. Not an expert so there are likely edge cases but one example would be a meadow where many different plants grow, flowering from early spring to late autumn. Introducing a new plant could mean it finds its own niche in this system or could mean that it completely takes over the whole system, reducing the overall flowering period to a limited time and thus causing problems for pollinators. If the latter is the typical result, the plant would likely become classed as invasive.
Typically when species migrated before humans invented quick transportation, their predators migrated with them. It didn't happen very often that a species becomes invasive without humans having something to do with it.