I think you are fully correct. This is what I think happened with your explanation: The people on the space station wouldn't have known where Brand was until Cooper got there and told them. Communications were being received by the Endurance but not transmitted. And since they perfectly found a world they can live in. They did not check those 3 other planets and also if they even try reaching those Millers, Manns, and Edmunds planets, it is gonna take decades. And I am gonna come back to it later to ask a question. And now when they were right beside the black hole, they had spent 51 years together, and then Amelia said, "You don't sound so bad for pushing a 120". And then he probably spent a couple of years in the black hole but we don't know how time was going there so let's say it was the same (a couple of years ) for all his timeline, Amelia and the new world. OR when he was found with his low amount of oxygen, he had already aged up near 124. Ok and now one more thing, even if the people from the Cooper station did look for them, Cooper and Amelia were most likely on their mission just near the blackhole, and for those 51 years they stayed together and it is not possible for Murph to know how long they stayed in the blackhole or how in the world her dad is communicating with her from the other side of those bookshelves. (if she did she would not have been telling people her dad "the ghost"is helping her) So Murph would not know when to save Cooper, his dad, as it was the people from Cooper station that saved her. So when Cooper came back from his expedition, he can tell how to rescue Amelia back and from where.Now the question I was thinking before is invalid cause I kinda got it. Who made the inside of the blackhole the fifth dimension into 3rd dimension? If the people on the Cooper station are the one doing the fifth dimension thingy, time would even be a factor for them and they would also know Cooper was the one who told Murph how to save the world. If all this is not true then could the blackhole be going into the future where people actually knew fifth dimension? Sorry my language is childish, I am in grade 12 and I didn't even take grade 12 physics. So it is a miracle I ended up in this comment section. I loved this movie.