This sort of thing provides good evidence that a COOLING TREND occurred in the fairly recent past.
It does NOT provide evidence that we are in a warming trend which should be a cause for concern.
It also does NOT provide any evidence that WE cause climate chance. If anything, it is evidence for the opposite.
I agree with part 1 and 3 of your post, but respectfully disagree with the part 2. We've known for at least a hundred years that we're in what we today call the "current warming trend" that begin around 1800 or 1850. We're still not back to what it was during the "medieval warming period" (roughly 900 to 1200 AD) and perhaps not as warm as the "Roman warm period" (roughly 200 BC to 400 AD). Both of those prior warm periods had many good things that we shouldn't fear. Things like higher crop yields, more predictable rain patterns, less plague, and more usable land that's not a frozen tundra (as this article makes clear).
Just like we shouldn't believe the political charlatans when they say we cause global warming, we also shouldn't fear it. We should look forward to all the good things it's brought in past warming periods.