“Ms. America” Chavez is a relatively recent addition to Marvel canon. She was introduced by Joe Casey and Nick Dragotta in 2011’s Vengeance. She was raised by her two mothers in a utopian pocket dimension. Her moms both appeared to die closing black holes that threatened her city, and inspired by their heroism, she abandoned her reality for the multiverse.
When she arrived on the main Marvel Earth, she joined the Teen Brigade and fought, among others, a teenage Loki.