Nah, just like most of the animals in that cave wouldn't survive outside of it, nothing from outside world would thrive inside of it: the conditions are too dif

Nah, just like most of the animals in that cave wouldn't survive outside of it, nothing from outside world would thrive inside of it: the conditions are too different. With low oxygen, and food sources that require extreme specialisation it's hard for any invasive species to take hold.