Well, we have to think like Riichiro Inagaki. We already saw before the incident that birds turned into stone when Taiju and Yuzuriha took the birds. We already know that it started in South America due to what Senku's dad estimated based off the tweets being sent. The stone is a sort of protective coat created from the metallic elements within the body. Senku came up with this hypothesis from a whole year's worth of experiments. I would expect it to be human made. It's probably an experiment. Then again, this is a manga/anime we're talking about. And that means it could be anything.
Though I don't think it will be a sci-fi or fantasy explanation due to the manga's nature. It wouldn't be like Riichiro Inagaki.
Also, how to do we know if we've won?
I think there already is a Discord.
I honestly would try to choose when I break out of stone unless someone frees me first. If I was able force myself to break free at a certain time, it'd be spring or early summer. If I was to restart civilization by looking for more people and hopefully a woman to repopulate the Earth. I don't have enough science knowledge to restart society like Senku. I would just share as many stories as possible and hopefully one of my descendants would figure out what to do. I would try to figure out what caused it, but I don't know how. I'd start making a hut for shelter, but I'd also make as many tools as possible. Since English is one of the most common languages I think I would lucky somewhat if I met a foreigner, since many languages have adapted English words into their own (Japanese has adapted "butter" and "beer" and German has used "handy" for cellphone). I would start thinking of all the scientific knowledge I could and I would write it done somewhere (maybe chisel it on a stone?). I'm in Ohio and there is a ravine behind me, so maybe I would be a little lucky to find food since there are berries back there, so in a few millennia there might be some more natural foods back there. And then there are deer that I could hunt. Without humans, deer and rabbits would breed quickly.
If I knew how to revive someone, I'd look for my dad first to revive since he is a pretty smart guy and he is strong. Or I'd look for someone else strong. I'd then look for someone I'd know who would be reliable.
I'd try to make as many plans as possible in case something goes wrong and develop them with another revived person.
I live like an 8 hour walk to Cleveland which is where Lake Erie, so I would try heading north. I'd see if I could find moss on the trees because I live in the Northern Hemisphere and moss here gross on the north side of trees and head that way. I'd probably camp out in my now overgrown ravine (3700 years have passed, it's bound to have grown huge). As I make my journey north. I'd review all information I could inside my brain and repeat as I head north west. I'd maybe make some kind of bag on my way to carry supplies.