This is a great post. However, according to your graph, first tool use occurred 3.3 million years ago. A quick google suggest Homo Sapiens have been around for approximately 300,000 years. So apply Fermi's paradox to a smaller scope - ask why we only see civilization within the narrow window of the last 10,000 years out of 300,000 years despite Homo Sapiens being in their current modern form for so long?
Here's a graph to help visualize the last 50,000 years https://www.dandebat.dk/images/1579p.jpg
Hopefully it's obvious that something changed coincidental to the advent of civilization - a very stable climate regime called the Holocene. We didn't develop the agricultural technology 10,000 years ago - the climate settled into a very unique period that allowed for it.
That period is rapidly drawing to a close. This is no longer possible:
"Today's civilizations will crumble, and many more civilizations will fall and rise."
Civilization depends on agriculture - it has never existed without it. Agriculture depends on a stable climate - it has never existed without it.
We're not leaving the planet. The likelihood of another Holocene occurring within the next million years, if ever, is extremely low. Here's another graph demonstrating how unique the Holocene is along with some pretty impressive technological feats by humans prior to experiencing a stable climate:
And here's the 400,000 year view - we don't live on a stable planet:
The skeptical view of Fermi's paradox holds - you get one shot at creating a sustainable civilization but the likelihood that entropy will swamp the required complexity is extremely high.