"Survival of the fittest" means "whatever doesn't die, wins."
First you need things capable of not dying in x circumstances. After adversity kills everything else, you have the "winners."
This will incline species to develop tolerance over time, usually several generations. Human caused climate change is happening on a timescale that isn't very supportive of that process.
RIGHT NOW there are coral that are already heat resistant. When the ocean temperature rises, the corals that can’t tolerate it will die off and the ones that can tolerate will survive. Then because of less resources being used by those that died, the coral with heat tolerance will thrive. This is how evolution works.
Dragonflies used to have like two foot or four foot wings spans. Now their relatively small and presumably play a very different role in the ecosystem.
Mother Nature isn't some Christian God that loves you and looks out for you. The fact that nature isn't looking out for our welfare is likely why things like Christianity are popular: Because actual reality scares the hell out of people and they need some kind of emotional opiate so they can go "La la la not listening!" and get through the damn day.