WARNING: The following contains major spoilers for Black Widow, now in theaters and on Disney+ Premier Access.
The biggest theme surrounding Black Widow revolves around family. One of the biggest mysteries is Natasha's past ties to her birth family. In the Marvel Cinematic Universe, it's revealed she never knew who her birth parents were, but Black Widows gives Romanoff more context to their fate. By giving more information about her mother, the film then makes a deleted scene from Captain America: Civil War non-canon.
In the scene "Extended Peggy's Funeral," Natasha comforts Steve Rogers following the loss of Agent Carter. While mourning, Steve expresses hesitation over signing the Sokovia Accords. To remind him of what is really important, Natasha tells him that she found her parents' graves while on the run in Captain America: The Winter Soldier. She explains she cleaned off the gravestone and left some flowers, impressing the idea that "we have what we have when we have it." While the scene itself isn't canon, the lesson still rings true.
In Black Widow, Natasha learns she was chosen from birth and sold to the Red Room to be a Widow. Even though Natasha's mother sold her, she was persistent in getting her back. Because she was making too much noise by trying to find the Red Room, Dreykov orders her assassination. He later explains to Natasha that she was buried under a tree with pink flowers, but her gravestone reads "unknown." On the other hand, Natasha's father is never mentioned and may or may not still be alive since he did not try to find Natasha.
Making the deleted scene non-canon helps Natasha's character feel complete in the larger MCU because it shows how she handles the topic of family without receiving closure regarding her own parents. Throughout Black Widow, Natasha tries to reunite her surrogate family while asking questions about her birth parents. It shows that her burning questions about lineage never left, but she knows the family she has currently is still what's most important, and it adds validity to one line from the deleted scene.
When Natasha tells Steve, "we have what we have when we have it," she refers to holding on to what is tangible in life and never taking it for granted. This is a belief Natasha follows from Black Widow until Avengers: Endgame because she knows the importance of keeping family together. While she failed with the Avengers, she didn't fail with her adoptive family in Black Widow. She held everyone she loved close until she couldn't anymore thanks to The Snap. In response to that, she chooses to sacrifice herself to bring everyone back, and fully negating that deleted scene makes her story and actions more impactful.
One of the glaring thematic issues of "Extended Peggy's Funeral" stems from Natasha already receiving closure with her parent's death. By the end, it presents a character who has tied up all of her loose ends and effectively completed a major arc in her story. However, thanks to Avengers: Endgame revealing that she never knew who her parents were, it shows there is still story left to tell, even leading up to her death. While the scene still plays up the importance of family, making it non-canon through and through helps Black Widow immensely because it shows she never gives up on her loved ones, whether they're staring her in the face or have long since passed.
Directed by Cate Shortland, Black Widow is now in theaters and on Disney+ Premier Access.