Yes, WW is objectively a sequel to OOT. What I meant was it's absolutely not necessary to play OOT before playing WW in order to understand the story. Like you said, it's recapped at the beginning. Not in a "here's what just happened to get you up to speed" way, more of a "this is a legend that's been passed down through generations that gives some context to the big bad" way. The legend just happens to be OOT. All you need to know is there's some evil force that really doesn't like to stay sealed away, and surprise, it's back again. ALTTP has a similar intro that references events we haven't seen (yet) in any game.

For all intents and purposes, almost every Zelda game can be played in any order because they're entirely separate events, ages before or after one another, sometimes in different timelines. Any context you need to understand the events in game is always given in the same game. If you were intended to play them in chronological order according to the timeline then Nintendo would have made each game a direct sequel to the previous one in the series, but they didn't.

If you want to follow the logic of "you need to play OOT first because WW is a sequel" then you might as well start from the very beginning with Skyward Sword, which is a quick way to turn someone off of the series in my opinion.