The Overwatch 2 devs have revealed tests for 6v6 to return and determine if the game should permanently go back to the old format.
Lol. After all these years they're thinking of rolling back the 5v5 changes. To quote someone from Reddit:
PVE was dropped, heroes are free again, and now 6v6 is back. Blizzard spent the last couple of years turning overwatch 2 back into Overwatch 1.
Edit: See also the developer's blog post about this, which goes into great detail explaining their decisions over the year and how we got here. Really worth a read if you are (or were) an OW player.
Iirc it had occasional pve events but the point of ow2 according to them was to have a permanent pve mode which iirc never happened but I haven't played in a while so take my words with salt.
There were holiday events, like halloween (junkenstein) and an anniversary event covering the robot invasion thing from lore. But I don't recall there being any permanent events, especially at launch.