I would say again that you're doing a good job poking holes in the theory. Honestly, I don't know what caused the MWP and the RWP. But: it's premature for you to declare victory just yet. The data you've presented does not "invalidate the concept of Global Warming," but at best permits a different conclusion. However: the theory that anthropogenic greenhouse gas emissions are responsible for the climatic changes we are experiencing today still holds. There is no other mechanism that fits the data as nicely.
As for "climate change" vs. "global warming" -- what exact catch phrase we use to describe the changes we are seeing is not all that important. If "climate change" was perhaps more accurate to say in the 2000s, when warming leveled off a bit, then "global warming" has returned in force with the readings taken in the 2010s.
What a lot of people don't understand about science is that it does not typically purport to offer be-all, end-all explanations (the way most religions do); instead, science constantly revises and even reverses its own conclusions as more data comes in. Scientists all around the globe including in remote and inhospitable places like Greenland and Antarctica are monitoring things very closely, and the vast majority of them are reporting warmer temps. No one can predict the future, but as of this moment, no other theory fits the data as well. As of right now, there's no excuse not to act to avoid living in a future world that is 2 or even upwards of 4 degrees Celsius warmer.
I followed the link, and appreciate you for bringing tangible debatable points to this discussion: however, I'm not sure it supports the propositions you cite it for. The authors appear to be just reporting results and aren't proposing any grand alternative theory to global warming. The authors even say this in the Abstract: "The temperature of the last two decades, however, is possibly higher than during any previous time in the past two millennia." The article was published in 2010, so it's not cutting-edge anymore. I have no opinion on Geografiska Annaler, and it may be a fine journal, but it's no Science or Nature in terms of prestige. There are better sources out there.