The Alternate Avengers Line-Up
What If...? Season 2, Episode 5 included a brief shot of an alternate universe's Avengers, and 11 years after MCU Phase 1's end delivered on Joss Whedon's lost addition. This episode revisited older ground as it picked back up on a story from last season in which Peggy Carter became Captain Carter and Steve Rogers piloted the Hydra Stomper suit. The Battle of New York sees Captain Carter wielding her vibranium shield capably alongside Black Widow, Iron Man, Hawkeye, and Thor. Joining Carter in being a non-original member of the first iteration of the Avengers, however, is Hope Van Dyne, AKA Wasp, who seems to have donned the suit to join the defense of Earth in this timeline.
Original Avengers including Hawkeye, Thor, Captain Carter, Iron Man, the Wasp and Black Widow assembling in What If...? Season 2
This alternate timeline apparently progressed similarly to the Sacred Timeline, with Loki leading a Chitauri invasion into New York against the Avengers. Except, this lineup of Avengers does not seem to include Hulk and has added a character that didn't don a suit until several years later in the Sacred Timeline. The shots featuring Wasp were brief and had no bearing on the wider story, but Head Writer and Executive Producer A.C. Bradley clarified on X the exact series of events that led to Hope's early adoption of the Wasp moniker.
Wasp flying in her suit in What If...? Season 2
Twitter article posted by A.C. Bradley
The Origins of Wasp in the Alternate Timeline
The rise of Captain Carter gave way to a wave of female empowerment, with more women joining the ranks of SHIELD, becoming heroes, and adopting leadership positions. As Peggy Carter was otherwise occupied as this timeline's Super Soldier, it meant that SHIELD had to be founded by somebody else - namely Hank Pym and Janet Van Dyne, alongside Howard Stark and Bucky Barnes, who was never captured in the war. These circumstances led to Hank and Janet's daughter, Hope, adopting the role of Wasp much earlier than 2018, allowing her to become one of the founding Avengers. This was part of Joss Whedon's original plans for the team.
The Original Avengers Plan and Its Homage in What If...?
The original script for 2012's The Avengers underwent several changes, but there was one draft in which Black Widow did not feature as the studio was not sure if they would be able to include Scarlett Johansson. In this version, Black Widow was replaced by Wasp, with Whedon writing several scrapped scenes in which she starred. This version of the script also had Loki's efforts bolstered by Obadiah Stane's son, Ezekiel Stane, as Whedon wasn't sure that Loki would be a big enough threat to stand up to the might of The Avengers. Ultimately, the ideas were rejected by Kevin Feige.
Interestingly, the original script is closer to the original Avengers lineup from the comics. This lineup, penned in 1963, included Iron Man, Thor, Hulk, Ant-Man, and the Wasp, with Captain America joining the ranks a few issues later. While Ant-Man and the Wasp in the comics were mantles held by Hank Pym and Janet Van Dyne at the time, it turns out that this What If...? episode was something of an homage to that original lineup, if only fleeting.