Climate has changed on all time scales throughout Earth’s history. Some aspects of the current climate change are not unusual, but others are. The concentration of CO2 in the atmosphere has reached a record high relative to more than the past half-million years, and has done so at an exceptionally fast rate. Current global temperatures are warmer than they have ever been during at least the past five centuries, probably even for more than a millennium.
If warming continues unabated, the resulting climate change within this century would be extremely unusual in geological terms. Another unusual aspect of recent climate change is its cause: past climate changes were natural in origin, whereas most of the warming of the past 50 years is attributable to human activities.
The climate has not changed much, yet! But in the past climate changes seem to have been driven by changes in atmospheric CO2.
The best analogue for our increase in atmospheric CO2 is the PETM, when CO2 increased by 0.2 Gigatonnes per year. We are increasing CO2 by 10 Gigatonnes per year, 20 times as much. See:
https://en.wikipedia.org/wiki/Paleocene%E2%80%93Eocene_Thermal_Maximum
So man-made climate change would not be unusual in geological times, only in terms of the Holocene = the last 10,000 years.
There is a tendency to assume that in the past the climate was stable, but that is only because we are look at average temperatures in the past and cannot see the abrupt changes. Certainly over the last 100,000 years the climate changed abruptly without the help of man. See this chart By Leland McInnes at the English language Wikipedia, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=6091581
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