My intent is not to diminish Thor. It is just to remind of context. Even the example you gave is about significant odds. We usually judge this sort of thing in that context.
Your are right that the ability to fight through despite all of that is key. However, I would still argue that this is more an exercise to play up lower tier characters than to diminish more powerful ones. They have to push harder in general that the more top tier guys in each situation.
Of course all superheroes have that gut check moment, some have many if they have been around in comics long enough.
I am just trying to explain my thoughts on what is meant. I do not think it is a knock on Thor, Superman or whomever else. It is more a matter of admiring the determination to heroes that may not even have powers in the first place.
If you're facing superior odds, you're facing superior odds. What does it matter how powerful you are if the odds you're facing are still superior to you?
Superior to Daredevil might be one of Spiderman's rogues. Superior to Superman might be a cosmically powerful being. But if Daredevil is fighting on in the face of probable death against the Spiderman villain, and Superman is fighting on in the face of probable death against the cosmically powerful villain, what's the difference?