You were never curious about how much they knew and were keeping from Luke?
Not at all. Other than Beru mentioning that “he’s too much like his father”, it never felt like there was anything there. From what we’ve known since then (early script\story\characters\Original Vision nonsense), there wasn’t anything there. Owen, Beru, and Ben let us know that Luke’s father was a good pilot, a good man, and was killed when Luke was young.
They were a character vehicle to get a farm boy out in the middle of nowhere and have him feel less attached to his family because they aren’t his parents. They’re in the film to add a bit of depth on our main character.
Since Vader wasn’t his father in the 70s, there was no reason to ponder anything that Lucas retconned about Luke’s parents in the 80s and 90s. I never gave them any thought because there wasn’t anything there in 1977.
I think Luke was related to Vader in some familial fashion already when the film was made. But yeah, Vader most definitely wasn’t Annikin/Anakin Skywalker in 1977, nor even in 78 pre-production for TESB. I maintain that Lucas didn’t make that switch until he started on the third film (or, very, very late in TESB’s post-production period). A Vader who is not Anakin/Annikin but is Luke’s biological father doesn’t explicitly contradict what Ben told Luke. No certain point of view required, or “metaphorical” death, since Annikin/Anakin would have been killed in this scenario as well. There probably was a ‘secret identity’ involved with Vader’s character, but this aspect was of course muted so that Star Wars could work as a stand alone movie, should the planned “books two and three” sequels not get made. To me, that’s where the whole “no there, there” comes in.