First things first. Congrats to England on the victory. Well played and they have showed without a shadow of a doubt what a quality side they are.
Second thing.
The series is not over. Whether England claim back the Ashes or not, no one will deny what a quality side they are. However, to gain appreciation as the best side in the world, a distinct possibility England face, the road is still a long one.
Firstly they have to win back the Ashes. A draw series will mean they would have to wait till the next Ashes in Australia to hope to get the title of the best side in the world. If they do get back the Ashes, they then have to have draws/victories in India and Pakistan. After that there is a fair possibility they will be called the best side in the world.
Exciting times ahead for world cricket.