I'll treat your question in two parts:
How close did the revolt come to 'proto-socialism'
Were the rebels goals attainable?
The peasants' revolt is interesting in the history of popular movements, not because it achieved particularly much, but because it laid the foundations for eventual parliamentary change, and for subsequent movements. It's important to understand that, for the most part, the rebels did not wish to abolish the monarchy. They wanted their reforms to be overseen by a sympathetic monarch. The revolt provides evidence of class war insofar as it represented both the rejection of an unpopular, unequal system of villeinage and an unpopular, unequal taxation and system of governmental representation. Although the outbreak of the great revolt had many contributing factors, it was primarily sparked by these inequalities. I'll skip over the long and short term causes of the revolt, however.
According to a marxist interpretation, the revolt fulfilled several of the elements of class struggle. Loosely, villeins could be considered to have been a 'working class,' and their relationship with the lords was certainly unequal. Henry Gibbins wrote an influential, if outdated, account England's industrial history, where he contended that a 'revolutionary spirit' was nurtured by important figures such as John Wycliffe, and John Ball.
So, were the rebels cohesive, and were they class conscious? Gibbins argued that religious leaders ‘combined into very effectual trade unions’ and that and that ‘[villeins and labourers] gained some consciousness of the power of labour.’
A Marxist historian might draw a parallel between two ‘revolutions.’ Firstly; the agitation of rural villeins and labourers against lords and landowners by literate clergy and ‘village élites’ in 1381. Secondly; the agitation of Russian industrial labourers against bourgeois landlords, amongst other things, in 1917. This comparison falls short, however, when one considers that the great revolt had no ambition to remove the monarchy. In fact, rebels wished to remove the intermediate class –the ruling class of lords – and instate an absolute monarchy.
An important example of the ideology of the peasant revolt is the 'oath at Bocking':
'[Men who met at bocking] swore an oath … that they would be of one accord in killing and destroying divers subjects of the lord king, saying and pledging that they did not wish to have any other law in England excepting only certain laws that they themselves put forward to be ordained.'
i.e. The revolters still wished for their to be an absolute monarch, only for that monarch to either be one of them, or to adopt their demands. In other words, while parallels can certainly be made to socialist thought, there was no real revolutionary agenda, and we can't consider the revolt to be 'proto-socialist.'
Now to address your other point, were the rebels' goals attainable? If we read the contemporary accounts on surface level, the answer is certainly not. The record of the events of the great revolt comes chiefly from chronicles: written accounts which are structured in chronological order. Authors of chronicles were necessarily highly literate, and therefore came from the either upper strata of medieval society, or ecclesiastical settings. As these two groups were targets of the rebels in 1381, extant chronicle accounts of the great revolt therefore contain an anti-rebel bias. The Kirkstall Short Chronicle, for example, doesn’t mention any of the goals of the rebels, and refers to the revolt as ‘this wild madness of those traitors’ whereupon the ‘community of the servile’ endeavoured to ‘subvert the laws of the land’ and ‘beheaded many of the more valuable members of the nation.’
the chroniclers largely portrayed the great revolt as an evil which overcame the common people.
we can infer from the inflammatory and religiously informed language of the chronicle accounts, however, that those is positions of power that were threatened by the revolt took it seriously enough to write almost endless diatribes against it.
Several of the rebels' goals would come to fruition, but only long after the fact. They were realistically attainable, indeed, but perhaps not within the generation of the rebels. For example, many of the ideas of the rebels regarding the redistribution of wealth within the church were to become key issues of the protestant reformation. Namely, according to the Anominale Chronicle: …that the goods of Holy Church should not remain in the hands of the religious, nor of parsons and vicars, and other churchmen; but that clergy already in possession should have a sufficient sustenance from the endowments, and the rest of the goods should be divided among the people of the parish. And he demanded that there should be only one bishop in England and only one prelate, and all the lands and tenements now held by them should be confiscated, and divided among the commons, only reserving for them a reasonable sustenance.
To conclude, the Great Revolt of 1381 did not constitute a revolution; indeed, none of the goals of the rebels were achieved by the revolt. It was manifestly unsuccessful during the lifetimes of the rebels, but undoubtedly contributed to the continuation of progress towards an equal society.
Sources:
Arner, Lynn. 2013. Caucer Gover and the vernacular rising: poetry and the problem of the populace after 1381. University Park: Pennsylvania State University Press.
Barker, Juliet. 2014. 1381: the year of the Peasant's Revolt. Cambridge, Massachussets: The Belknap Press of Harvard University Press.
Dodd, Gwylim. 2006. "A Parliament full of rats? Piers Plowman and the Good Parliament of 1376." Historical Research 79 21-49.
Gibbins, Henry de Beltgens. n.d. The Industrial History of England.
Primary Sources:
Froissart. n.d. Tales from Froissart. Edited by Steve Muhlberger.
McHardy, Alison, ed. 2012. The Reign of Richard II: From Minority to Tyranny. Manchester University Press:
Anominale Chronicle
Kirkstall Short Chronicle 64-65
Vita’s Account 66-71
William Thorne’s Chronicle 75-76
Dunstable Annals 84