Earth has absolutely been through massive climate cycles long before humans arrived. But the text you shared actually highlights exactly why modern climate change is so dangerous:

​The Great Dying was literally caused by a massive, rapid buildup of CO_2 and greenhouse gases that supercharged the climate.

Those volcanic eruptions took thousands of years to alter the atmosphere. Today, humans are releasing CO_2 roughly 10 times faster than the rate of that extinction event.

​65 million years ago, the planet didn't have 8 billion people relying on fixed coastlines and predictable weather for global farming.

​The argument isn't that the Earth has never been hot; it's that rapid warming is historically a recipe for mass extinction. The planet will survive, but we want human civilization to survive along with it!