It's a poor choice of wording there. Agreed.
But why would you use "one" if it means "any one" or "all" or "each"?
I of course don’t know for sure why they weren’t clearer, but to be fair to the writers, in English many short constructions of this rule are potentially going to be ambiguous. For example, if I said “you can replace each attack with a shove” or “you can replace all your attacks with shoves” someone might think that if you elected to shove you had to only shove and not attack. And “you can replace any one attack with a shove” doesn’t seem to mean anything different from “you can replace one attack with a shove” though it might have a slightly different implication.
In the clarifying tweet I linked above, Jeremy Crawford said “If you take the Attack action and have multiple attacks, you can replace any of them with a grapple/shove” which doesn’t include the word “one” at all but still seems consistent with both possible interpretations, though folk in one of the other links I posted clearly took it as definitively meaning that multiple attacks per turn could be replaced by shoves. The construction in the RPG citadel article that says fighters “can use shove to replace any and all of their attacks” is unambiguous, but I don’t think we can use the fact that isn’t said in RAW to imply that this wasn’t intended, given it’s consistent with RAW.
In case it’s not clear, I’m not arguing that one interpretation is right. I have no idea and am not qualified to make a call, and to be honest I don’t think I much care one way or the other beyond wanting to understand what the rules as intended actually were. Unfortunately I don’t think that’s going to be answered unless someone is aware of a less ambiguous WotC source somewhere that clarifies.
