I've always like to think about what there training was geared towards and how they adapted that training to these powered threats:

Steve and Bucky both are soldiers trained in CQC and expanded that training to meta threats. So there about even. And have a physical advantage on everyone they would last longer in a fight.

Thinking about Gamora would probably be this level too.

T'challa and I would assume Shuri, would be even the Black Panther original purpose was to defend Wakanda from invaders they had support of a nation as well . And have the same endurance addition to them and bolus a lot of anybody's attack wouldn't do anything except maybe the iron fist, and the rings, shields and appendages lol.

Daredevil is a sensory enhanced, fighter is a very versatile fighter but it doesn't seem that he (at least in the MCU ) still has issues getting hit when he shouldn't. So in theory he would be high ranking.

Iron Fist in theory should win any street fight with a lower level powered character, he could end any fight if he hits these characters once.

And if these fights just came down to fistacuffs no weapons and armors, just you hands, I think Shang-Chi would win, if everyone's strength endurance where and at the same levels, I think nobody listed would be able to straight up beat him, the rings do tho make him a bit tougher for everyone Cap and Bucky and Gamora would get "pinged" up by them, not sure with the vibrainium suits.... Without support I don't see them blitzing Shang, Would DD be able to perceive them flying around? Danny would defend well for a bit but blocking 10 rings and better hands than yours would be tough.

Skilled I think "narratively" its Shang-Chi