I think the closest widely spoken accent to what was spoken in England a few hundred years ago is southern American IIRC. I think there’s actually an island in Virginia that is almost totally isolated, and they have what we suspect is the closest.

It’s still all accents obviously, but if you mean the least changed from what it used to be at one point (which is different than what it was at a different point), you are mostly correct. Obviously there are still a million variations of American accents, and even a lot of variations of the southern American accent.