How could Star Wars have been always about Vader's redemption if he wasn't originally going to be Luke's father?

You do realise that Lucas is just making this stuff up as he goes along don't you?

Sure ESB shifted the story around but it's only when the PT was announced and Anakin was cast as the little chosen one that the whole thing being about him line popped up.

Before that it was a story about wars in the stars of a galaxy far, far away a long time ago.

Why that should end just as the interesting characters succeed in a major victory is genuinely beyond me.