While this graph does show that the overall trend in global temperature has gone down throughout history, it willfully misrepresents the problem of global warming we face today. This graph shows temperatures over hundreds of millions of years, but if you look at the very end of the graph, you can see the upswing in temperature in the current chapter of human history.
https://climate.nasa.gov/vital-signs/global-temperature/?intent=121
This graph by NASA shows recent temperature changes, and we can see that in the past 100 years, global temperatures have gone up about 1.25 degrees C, so global warming is still very much a problem in modern times.