We are, in fact, in a mass extinction event right now, with extinction rates estimated at 1-2 orders of magnitude greater than any previous such event.
https://en.m.wikipedia.org/wiki/Holocene_extinction
> If you can see the sun, we shouldn't have all these animals dying.
Not all previous mass extinctions have involved the sun be blotted out by impact or volcanic events, though several have.
As long as you don’t have any attachment to anything more narrow than “all life on earth” (e.g. your family, language, city, country, culture, species, ...) thriving for a long time into the future, there’s no reason not to just shrug at whatever impending apocalypse.
No, they haven't; extinction rates in the current mass extinction event are much higher than previous ones.
If we always preserve what we have, there will be no room for something new to develop.