This study does not support your conclusion, and so adds no evidence to support that conclusion. It's not even studying the sort of diet you're talking about!

> I meant having a precise definition of processed didn't matter for the question what our diet should be

No, it really does matter. If you're trying to argue that some specific food or processing technique is bad, then a study that had all participants consume it can't be used to show that it's actually harmful. And by your definition, that's what this study did - it had everyone consume highly processed foods, and some of them had good outcomes. That undermines your conclusion; it does not support it.

Perhaps the above comment is accurate in the sense that a raw, paleo diet is healthiest for humans, or even the only truly healthy diet. (Though I've yet to see any strong studies claim that it beats a Mediterranean diet, much less a great many studies.)

But even if that's true, it's an entirely different question from "what's up with modern ultraprocessed foods?" This study was contrasting foods like "normal" pasta with canned ravioli and finding a difference. Since "everyone only eat raw food" is an unlikely and unpopular outcome, it's absolutely worth finding what's actually problematic within the enormously broad sweep of "processed".