Thragg has been damaged again and again. He has even been disembowled. And, yes, he has fought on.
But, there is no way to quantify the threat posed by the Ragnar. The hype given to them, is no more than the hype that the Mindless Ones used to get in the Marvel universe. And look where they r now.
The problem still remains that he, by comic book standards, is easily damaged by heavy hitters. And this level of damage is not seen as casually in marvel or dc.
And, even though Thragg fought on while disembowled, the fact that he can be damaged so easily, opens the door for scenarios like "dismemberment". Thragg can not continue fighting if he loses too many limbs.
So, we know that the Invincible universe is going to depict it's characters as being far easier to damage than in marvel or dc. Which, in my opinion, is a "plus" and adds to the stories.
But, on paper, in a debate, this will ALWAYS work against them, when going up against a marve/dc heavy hitter. Because, the fact is that we can show far more instances of Thor/Supes going up against enemies equal to, or far above Thragg in power, without sustaining damage anywhere near the damage Thragg and others sustain on a regular basis in the Invincible universe.
So, really, what r we supposed to do, ignore the durability aspect? Because thats the only way Thragg and the rest r going to get an equal chance in these debates.
Personally, Id b fine if they were kept separate, the way Dragon Ball characters are. And I hope the Invibcible stories and character aspects never change.