In MCU, contrary to the others, Clint Barton and Natasha Romanoff are mere humans with good training and combat abilities.
Other members like Hulk, Thor, Cap, Vision, Scarlet witch ,Ant Man have at least some kind of superhuman abilities respectively, moreover with his armour Iron man (and possibly Falcon) has the ability to achieve much more than ordinary human can do.
My question is, with a team of members with superhuman abilities like that, why do they need Hawkeye and Widow?
I know they are both master combatants and the widow is an amazing spy. I am aware that in comics, they were Avengers, even Hawkeye was earliest member of team. But not all founding/earliest members were in Avengers movie duology (yet).
I wonder why did they use Barton and Natasha in the movies, with other guys who each had superhuman ability(s).
What is the significance of using them in MCU?