It is very interesting how your story has many elements that I heard before but also brings new distinct details I see for the first time.
Have you heard about the hypothesis that our planet actually has 2 major competing CF right now?
That our planets own CF is being undermined by a foreign CF that arrived around 80k years ago.
The reason why a non-host human seem automatically vile is because the foreign CF is specifically targeting humankind to take over the planet. It expands the field through the specific technologies that our cities are full of.
But it looks like non-human non-hosts are not affected to the same degree that humans are. That most animals and plants are still strongly connected to the planets original CF which isn’t vile. Nature doesn’t seem to have the same “vile” type of CF and that is why a high number of extraterrestial/extradimensional encounters happen outside cities, in nature.