The pound sterling of 2019 is more related to the American dollar of 2019 than it is to the pound sterling of even WWII, nonetheless 800CE.
The ship of Theseus isn't a fallacy, it's a thought experiment.
And additionally the American dollar is not the same as it was pre bretton woods, or pre federal reserve, etc.
Not really. It’s just a matter of changing times and prices. Pounds and pennies have been a thing for 1200 years. What they buy has changed dramatically.