The ideas of the Diggers and Levellers were certainly revolutionary and we can take inspiration from them today. Yet their support base was the threatened petit bourgeois and army. That is why the revolution could not have been taken further.
A socialist revolution was impossible in the absence of an industrial working class and the further development of capitalism. It was an early bourgeois revolution where - as Harry Pollitt put it - "the growing capitalist class … led by Oliver Cromwell, shattered the system of feudalism." As the leader of that revolution, Cromwell deserves our respect.