I think you're sad that the world is too complicated for you to know everything and that you have to trust other people about things which you don't know about
I'm saying that in order to appreciate something you have to understand it. Most people have an understanding of temperature records whereas most people do not have an understanding of ice core isotopic temperature proxies.
Ice cores, speleothems, I think things like tree rings and pollen have been used? Probably things like corals and other biological remains as well. Climate isn't my field but I'm familiar with some of what is done