Lemme address these, cause I do agree with these, but I disagree with others.
1. Well, N'Zoth didn't really "beat" us. He was about to corrupt us, but Magni's "hero" speech and our Titanic willpower kinda fucked his corruption over.
2. Well, Archimonde didn't really lose to the Wisps. He really lost to the ritual that involved the Tree's magics being used against the Defiler, cause, if you forgot, the Aspects blessed the World Tree. Also, Khadgar, Yrel, and Grom did aid us, yes. However, we mostly did the heavy hitting, thanks to our Legendary Rings. With Kil'Jaeden: Illidan only aided us VIA giving us sight against Kil'jaeden's eternal darkness ability. Outside of that, Velen, Illidan, and Khadgar were on the sidelines, facing all the adds while we fought the Deceiver alone.
3. Argus, we did have help, yes. However, outside of the Aggramar Avatar thing Tanks got, and outside of the Titanforging amps, the Titans merely aided us VIA using their magics to cleanse the battlefield, or to resurrect us. Only 2 of them gave actual power boosts, and one of them happens when Argus gets canonically amp'd up by Sargeras' power. Also note that Sargeras himself was attacking us from a distance during the battle, so, even with the Titan Spirits and their aid, it's crazy how we managed to live all that.
4. Med'an still got empowered by Jaina, Aegwynn, as well as other Mages in order to fight Cho'gall. Meanwhile, us Champions, while fighting as a group of individuals, weren't empowered by anything really during our battle against Cho'gall. So, it's not like Med'an was all on his own there either.
I know we're not "lone survivors". I'm just saying that us in general are very powerful guys, with aid or otherwise.
5. While that is true, in the more recent Expansions however, we have been aiding the more powerful lore figures, rather than the other way around.
6. Well, that's not all around true tbh. Especially considering we're basically Avatar's of Azeroth's Titan herself, capable of activating ancient relics of the First Ones, etc etc.
7. I GUESS it's consistent, but when you jump from struggling against N'Zoth with the HoA, to fighting Titan-Titan++ Level threats the expansion after, without the HoA even, then you're getting kinda inconsistent.
Hell, the LK used to be a foe weaker than the Legion. Now, he's stated to be an Agent of the Maw, and that he had the potential to destroy all the Shadowlands. Hell, Chronicle implied that the LK was preparing to take on the Legion.