Maybe it’s just me, but when I watch these movies it’s easy to compartmentalize. When I watch ANH, I rarely if ever have the events of RO or the prequels in the back of my mind. Whether they ‘ruin’ the story of ANH is irrelevant to me, they’re separate movies - I’ve always enjoyed the original SW as a movie on it’s own and there’s nothing stopping me from doing that.
On the other side of it, RO is obviously stretching the bounds of what could technically have happened with the dialogue from ANH in mind. But you know what? Who cares.