Interestingly, the Law course (actually Jurisprudence) at Oxford may be best suited for Americans NOT intending to be practicing lawyers.
Even in the UK, it has, shall we say, not the best reputation in terms of practical training. And while it is fine to go to Oxford for undergrad and apply to US law schools, for that purpose I would pick something less on the nose, like say PPE (really a greatest hits of majors popular before US law school), or Classics (arguably the best single major to actually prepare you for legal reading, and at Oxford!), or Geography (a legendary, and really cool, interdisciplinary course at Oxford). Or just something fun!
But if you were thinking of going into government or business or something, I could actually see Oxford’s Jurisprudence course being a kind of cool outside the box choice. You’d actually get a kinda broad overview of a variety of different legal systems, and I could see that actually being a valuable background for careers which are less about practicing law, but do involve frequent dealings with a variety of legal authorities, or indeed creating law.