Its amazing how it took the giant volcanic eruptions and the Yucatán Peninsula impact to cross the 20°. Also interesting that after a warm period at 20° follows a cool down period at 10°, with the exception of jurassic/cretaceous cool down, that only reach right below 15°, do you believe it was the super-continents split and the creation a two massive oceans what balanced the temperature?
Average global temperature in 2018 was close to 15°, the last five years has been the hottest on record, showing an exponential warming rate; I am afraid as you said, there is nothing to stop earth from keep getting warmer... maybe we will need another re-engineering by the Anunnaki

Interesting video (animated map) that shows the history of temperature changes around the world from 1850 to 2018:
https://youtu.be/JObGveVUz7k