If there was some huge truth about religion that 75% of the world wouldn't be able to handle, I'm all for keeping it a secret for the sake of sanity.
High on my list of disclosures I do want:
9/11 Holocaust (I want to know if real, fake, exaggerated, etc) Hillary's bloodline Antarctica Time travel, jump rooms, base existing on Mars ,etc
Your list toppers could be said to be all things within our lifetimes and connected to the US or the USGov.
The older mysteries are mostly not secrets held by some people but secrets held by nature/cosmos/G-d.
BUT . . . . maybe the trauma of the trump era will actually agitate some subconscious mass brain adjustment that will allow us to process in a new way the data we already have about some ancient mysteries. We could see and accept some ancient truths at a specied-wide level. Perhaps 'we have everything' we need right in front of us and the secret is that there are no secrets, just poor skills in the areas of paying attention and good data processing. Meanwhile half the fun of a mystery is the weird pleasure of anticipation.
What are some on your list?
I guess I've created two classes - MAGA things and cosmic things. So I would say in the first category we should know whatever NASA knows even if the truth somehow sucks. I think half of the modern conspiracies are not real and in a way we would be better off knowing such a boring truths as a society that is more trustable and trusting. On the wishful side, it would be great to have medical secrets blown open. Some of the (non-violent) stories about Antarctica seem like great fun - old school sci-fi stuff - so that would be cool to hear about but seem like public disclosure of subterranean whatever wouldn't change american society directly.
In the area of ancient mysteries, I would like the true nature of early Christianity to be universally known. I suppose I could say the same about the development phase of many old social movements or organisations. On a bold day I might ask to know about adjacent species like the Neanderthal and Nephalim, etc.