She also knows
Her message ends: "This is our most desperate hour. Help me, Obi-Wan Kenobi. You're my only hope." Obi-Wan is visibly emotional as he watches the message – and now viewers think the moment has taken on a new meaning thanks to the series.
Throughout her encounters with Kenobi in the series, he refers to himself as Ben. The most straightforward explanation would be that Leia knows the person who rescued her is Ben, and never connected the dots that Ben is actually Obi-Wan.
Obi-Wan came to the Death Star to save Leia from the Empire's clutches, but was killed by Darth Vader while the others were busy escaping. Leia didn't see Obi-Wan again, nor did she experience any sadness when she learned of his death.
During the iconic opening moments of Star Wars: A New Hope, Darth Vader has a tense confrontation with Princess Leia, an adversary who, unknown to him, is actually his daughter. Despite participating in Leia's interrogation, the Sith Lord doesn't uncover his familial connection with the rebellious royal.
Later, the heroes go to the forest moon of Endor to prepare for a battle with the Empire. There, Luke reveals to Leia that she is his twin sister and that Vader is their father.
Darth Vader didn't learn he had a daughter until Return of the Jedi, when he stood before Emperor Palpatine. The Emperor's power probed Luke's mind, attempting to goad him to fall to the dark side, and he discovered Leia's existence.
Vader learned that Leia was his daughter by sensing it from Luke in Return of the Jedi.
In A New Hope, Leia's utter faith in Obi-Wan Kenobi comes circuitously from her father, who, in that film, is never glimpsed. However, when Luke breaks Leia out of her cell and says, “I'm here with Ben Kenobi,” and Leia doesn't miss a beat. She knows that's his other name.
Why does Obi-Wan Kenobi age like that? Because he's not real, and is a fictional character played by different people. You see, Obi-Wan Kenobi is played by Alec Guinness in the original trilogy. Guinness was 62 when he filmed A New Hope, and he died in 2000.
Obi-Wan greets R2-D2 and later recalls “not owning a droid.” Obi-Wan purposely withheld information from Luke in order to keep Luke from straying away. This could offer an explanation as to why he appears to not know who R2-D2 is. Further in Empire Strikes Back, neither Yoda nor Darth Vader recognizes either droid.
His memory was wiped at the end of Revenge of the Sith. A blabbermouth like him can't be trusted with sensitive information.
Leia does not seem to react to tragedy. Instead, she has this wonderful ability to stay perfectly alert, reasonable, and careful of the feelings of others. She witnessed the destruction of her entire planet, and still had the mental and emotional strength to escape with Luke and Obi-Wan.
She's important in the plot sense because Reva, who is searching for Obi-Wan for Anakin, uses Leia as bait but she's also important because she reminds Ben what he lost in Padmé and Anakin but what he gained in the twins. Leia is just as important as Luke.
The first time, Obi-Wan tells Leia she reminds him of someone “fearless and stubborn,” a “leader who died a long time ago.” While it's possible he was referring to Satine Kryze (voiced by Anna Graves in the Clone Wars animated show), it seems more likely he was talking about Padme.
As Leia confidently walks into the hangar and chides Obi-Wan for not trusting the person offering them help, he stops and says she reminds him of someone. However, there is another woman in his life who he might be reminded of, the love of his life, Satine Kryze.
However, rather than be an oversight or plot hole, Leia might not have remembered old Ben for one sinister reason. This has to do with Ben's Jedi powers, namely the mind trick. As he grew older, he'd use it on Stormtroopers to protect Luke Skywalker.
Obi-Wan Was Pretending He Didn't Know R2-D2
The base assumption of why Obi-Wan doesn't remember R2-D2 -- in light of the prequels -- is that Obi-Wan is feigning ignorance in A New Hope to downplay the importance of the droid's arrival.
Arguably, most Star Wars plot points revolve around characters simply not knowing something, very often about their family history. But, on top of all of that, the biggest reason Obi-Wan doesn't know Anakin is alive is that the last time he saw Anakin Skywalker in Revenge of the Sith, Ben literally left him for dead.
Reva knows that Anakin Skywalker is Darth Vader because she was one of his targets—a child—during the Order 66 killings that took place during the events of Star Wars Episode III: Revenge of the Sith.
In Legends, Luke and Leia do eventually discover their mother's identity during the Swarm War Trilogy.
In Legends they did talk, but they did not reconcile. Anakin approached Leia as a Force Ghost and apologized for what he did to her as Vader. She basically told him to go away.
While their affection had to remain hidden, the two kept in frequent contact, even throughout the Clone Wars. But despite this, Anakin found out that Padme was pregnant only a couple of weeks before the twins were born. So, why did it take so long for her to tell him?
It's hard to say for certain - but even if Vader was aware of Yoda's existence, chances are he probably did not know where Yoda was; being the Jedi Master that he was, he had an exceptionally strong connection to the force - and so, he could have easily hidden his location and energy in the force whilst on Dagobah, all ...
It's well known that Star Wars lead characters Luke Skywalker and Princess (now General) Leia are brother and sister. The estranged siblings didn't know about their familial relationship until "Return of the Jedi." They even shared a passionate kiss in the previous movie, "The Empire Strikes Back."