You are directionally correct though these climatic oscillations typically take place over multiple centuries, not decades. That and there have been dramatic climate shifts in every epoch. Though the Holocene has been relatively stable and relatively warm - something humanity is currently taking for granted.
There have been periods with much faster temperature rate of change (vs the past 150 years that humans are worried about) and the atmospheric temperature maximums have been significantly higher during some of these periods. All have reversed on their own via mechanisms that aren’t fully understood by humans. All have happened with no human co2 impacts.
The earth’s atmospheric temps are cyclic and completely out of humankind’s control. We have other stuff to worry about and there are things humanity can address and impact now.