Nobody got sick.
It turns out that the critters that infect people are usually pretty specialized and have a hard time living in dough.
humans are kinda salty.
As I understand it, there are two things going on. First, most (or even all?) pathogens can’t tolerate alcohol, and many baking yeasts produce alcohol. (Many sourdoughs produce very little, though.). A lot of pathogens also can’t tolerate the acids in sourdough either. Most importantly, baker’s yeast and sourdough cultures grow fast. The outcompete the nasties in dough. This is why a brand new starter can be funky, but this resolves itself after a few generations.
Same broad taxonomic Order but way different lineages in the same way that bears and corgis are in the same order. Similar enough -- fur, teeth, etc. -- but one is a useful friend, and the other will try to kill you, though serious threats are kinda rare.
If this was bread yeast, even old bread yeast, it'll probably be harmless, in the same way that the reincarnation of an ancient Egyptian cat will probably just act like any other cat.