I MADE A TIMELINE! After my original post I just had to sit down, prepare my brain for mental combat, and go for the big guns. This information all comes from official Overwatch hero bios, videos and articles, as well as interviews and panels from devs, so even if some of my estimated dates (which you can identify using the timeline key) aren’t 100% to the year the chronology should make sense, and the events are all canonical.
-pushes up glasses-
Alright y’all! As always I hope this is useful to you, and feel free to contact me should you have any questions!
EDIT: Whoops! I had accidentally misplaced the Shimada brothers’ information, and felt it was more appropriate to remake this post rather than to have the original erroneous one circulating. Terribly sorry, please refer to this one instead!