If we ARE going to be honest, let's at least consider the facts:
Flash was around 24 years before Quicksilver entered the scene.
Green Arrow predates Hawkeye by 23 years.
Black Canary was introduced in 1947, Black Widow arrives in 1964
Atom appeared in comics 3 months before Ant Man.
Some others? Batman appeared in 1939, Iron Man not until 1963 (Billionaire heroes)
DC's Captain Marvel appeared in 1940, Marvel's Captian Marvel shows up in 1967
So now you know.
Does it really matter? LOL, no. I think each character has their own appeal and interesting origin stories. Each one is an entertainingly fun escape from reality. Cheers