“Invasive” is a useful concept to describe species that spent millions (sometimes hundreds of millions) of years evolving in one environment and then moving to a new one in the last few thousand years.
replyDo you understand that time scales are important here?
There are also species that have invaded areas that are totally impossible for them to reach without seafaring or airfaring human civilizations to carry them.
All terms are made up. Some are useful and some are not. This one is useful.
The usefulness of the term to this conversation is as described: is this species systemically critical to its current ("invaded") ecosystem?
replyMerely calling it invasive does not answer that question, ergo it is not a useful term in this conversation.
And yes, timescales do matter. A species can become critical to its new ("invaded") ecosystem within a few hundred years such that removing it within a few years will cause catastrophe.