No......it was extremely hot before the ice age. Do you seriously think the dinosaurs were just hanging out in 70 degree weather?
Look at insects, as oxygen levels decreased they became smaller. Even alligators used to be like 150 feet.....now they're closer to 18-30 feet depending on type.
The living creatures of that era were all bigger. It was more humid. There was more oxygen in the air. And then astroids hit, and basically were world ending events. Happened twice, hundreds of millions of years apart.
And you think that YOU can kill a planet? No. This planet decides if it ALLOWS you to live. And humans are awful pests. Honestly surprised the 2 nukes in WWII didn't trigger a 3rd ice age.
But until the 3rd ice age, it's just always going to get hotter. Humans or not.