In Marvel's comic world, many heroes have the benefit of being an alien, having powers, or both; however, there are more than a handful of heroes that have proved themselves just as heroic as any superpowered individual on the battlefield. While many of them you may recognize from the movies (Black Widow, Hawkeye, Iron Man, etc.), we're also going to take a look at heroes that are not so well-known. I've split this into two articles, due to the surprisingly large amount of civilian superheroes, so be sure to check out 'Part 2' when you're done here.
Formerly a Mutant, Alejandro Montoya was de-powered on M-Day, but still retains his master swordsmanship and hand-to-hand combat skills.
As a soldier, martial artist, and pilot, Andrew Chord trained Dwayne Taylor as he became Night Thrasher (out of guilt from killing his parents). Chord had a large influence in Night Thrasher's decision to form the New Warriors team, even serving as pilot and trainer for the team.
Trained by the KGB at a young age, she is one of the world's greatest spies, athletes, assassins, and a master of disguise. Black Widow is commonly seen wearing two bracelets equipped to discharge high-frequency electrostatic bolts, lovingly called the 'Widow's Bite,' which are capable of stunning a superhuman opponent, shooting tear gas cartridges, and acting as a radio transmitter. She is portrayed by Scarlett Johansson in the MCU (Iron Man 2, The Avengers, Captain America: The Winter Soldier, Avengers: Age of Ultron).
Bucky Barnes is an Olympic-class athlete, acrobat, marksman, martial artist, and assassin. Presumed dead after the plane-hopping mission that led to Steve Rogers' time as a Cap-sicle in the Atlantic, Bucky was resuscitated and trained by the Russians to be the Winter Soldier, committing political assassinations that had huge effects on the Cold War. He is portrayed by Sebastian Stan in the MCU (Captain America: The First Avenger, Captain America: The Winter Soldier, Avengers: Age of Ultron).
Another former Mutant gone normal after the effects of M-Day, Alleyne remains with his team despite his lack of powers.
Master assassin, Olympic-level gymnast, and martial artist, Elektra Natchios possesses strength, speed, agility, reflexes, and endurance at the pinnacle of human performance. She will be portrayed by Elodie Yung in the MCU (Daredevil Season 2).
Merely a rooftop-swinging athlete until the Black Panther provided him with Wakandan technology that enabled him to truly fly, Sam Wilson is a regular ally to Captain America and the Avengers. He is portrayed by Anthony Mackie in the MCU (Captain America: The Winter Soldier, Avengers: Age of Ultron, Ant-Man).
Orphaned at an early age and trained at the Carson Carnival of Traveling Wonders by the original Swordsman (Jacques Duquesne) and Trickshot, Clint Barton is a world-class archer, martial artist, marksman, swordsman, and pilot. His above average reflexes and hand-eye-coordination make him the most proficient archer ever known. He is portrayed by Jeremy Renner in the MCU (The Avengers, Avengers: Age of Ultron).
Computer expert, programmer, and researcher for the New Warriors, Carlton LaFroyge was Speedball's former college roommate and has been an instrumental part of the team, even just from his computer.
Staying in the Savage Land as its self-proclaimed protector, Ka-Zar is an expert hand-to-hand fighter and possesses great strength and acrobatic skill. He is also a skilled tracker, climber, and swimmer and is accomplished in animal handling and wilderness survival. Ka-Zar is often seen with Zabu, the saber-toothed tiger who raised him from an early age.
A proficient acrobat, martial artist, expert with a quarterstaff, and possessing killer espionage skills, Bobbi Morse is a S.H.I.E.L.D. agent with skills similar to those of Black Widow. She is portrayed by Adrianne Palicki in the MCU (Agents of S.H.I.E.L.D.).
Martial Artist, millionaire, trained mercenary, assassin and marine, Marc Spector is Marvel's version of Batman, albeit with Multiple Personality Disorder. An idol of the Egyptian moon god, Khonshu, saved Spector when a mercenary mission in Egypt went wrong, giving him his moon-based powers.
There's more where that come from, so be on the look out for Part 2.
Sources: Marvel Wiki,Marvel