I don't consider Miura a supercar because it was genesis for the mid-engine flamboyant Lamborghini V12 cars. Altough I consider those supercars as well. The Murcielago especially is the last of a line, an old-schooler.
However imagine this. You are in 1966. You live in Modena and you drive a Fiat 850 Super with 37bhp and a top speed of 125km/h. Your idea of a high performance sportscar is a Ferrari 275 GTB with a 280bhp V12 engine or a straight six engined 255bhp Maserati Mistral. Both were conventional front engined cars and the Maserati even had a live rear axle.
And then along comes a car with the engine mounted in the middle behind the seats, with the gearbox and engine sharing the same oil à la Mini because there wasn't much space. With a striking body and a 350bhp V12 engine. A car that wasn't derived from race car or related to one in any way.
The Miura for itself could be considered a supercar. History is important, but in its time it was something quite special indeed.
Lack of charisma can be fatal.