One thing that’s made clear in the Warcraft universe is that many of the things our characters do are non-canon, but rather gameplay mechanics taking priority over lore.
Conjuring mage portals and casting battle rezzes are portrayed lorewise as things that are extremely difficult, if not impossible by some people, to perform.
And self-rezzes via “returning to your body” just outright don’t exist lorewise. They’re there for gameplay reasons because a game where death is permanent would be…well…nearly unplayable in an MMORPG.
So…what does this mean?
This means that with the exception of certain “scripted” deaths (ie; Lich King and Argus deaths), our characters have literally never died ONCE.
So consider all the tough bosses we faced, from C’Thun to Yogg-Saron to Arthas to Deathwing to N’Zoth in his unleashed form to literally every other boss we fought.
Some of these bosses took WEEKS to kill, if not outright MONTHS!
These are the hardest “lore” enemies in WoW, and many encounters were certainly structured to make it feel that way.
The only way these bosses were eventually killed was through trial-and-error. Guilds would go up against these bosses, wipe, learn from their wipe, try again, wipe again, learn from it, improve, do better, and with skill and practice, they would eventually kill them.
But if death and player resurrection in WoW is non-canon, then what this means is that our ragtag group of adventurers literally fought these bosses ONCE, and on their FIRST try against the most powerful enemies in Azeroth, they were able to destroy them.
Lorewise, there was no “trial and error” where the adventurers “learned” and “improved” until they were eventually able to win.
They just went in BLINDLY (accurate adventure journals and YouTube guides don’t exist in lore) and stomped on the bosses with relative ease on the same day they first even merely SAW many of the bosses (C’Thun, Yogg-Saron, etc).
Thus, our characters are Mary Sues.