I guess we're approaching more literature than history, anyway here's my answer:
First thing, you have to differentiate Jean Valjean and Edmond Dantès from Henri Charrière. The first two are fictionnal characters living after Napoleon's Empire, during the Bourbon Restoration and the July Monarchy.
On the other end, Papillon [pub. 1969] is supposedly an autobiographical novel during the interwar period. So the political and societal context is extremly different for Henri Charrière.
Obviously, on a narrative level all three are dealing with redemption/revenge and false (or arbitrary) accusation themes (Stephen King would use such themes later in The Shawshank Redemption and The Green Mile).
So, I don't think this subject is "outsized" but it certainly reminds of republican ideals and ideas during the 1840's -Republic wasn't the regime at that time- and mostly echoes with the french (and haïtian) motto "Liberté, Égalité, Fraternité" (Liberty, equality, fraternity). One of the primer reference is in Maximilien de Robespierre's "Discours sur l'organisation des gardes nationales" in december 1790.
Robespierre, Maximilien (1950). Œuvres de Maximilien Robespierre, Tome VI. Discours (1ère partie) 1789-1790, Paris, Presses Universitaires de France, 1950, p. 643 [read on line].
See also: "Liberty, Equality, Fraternity" article on the Embassy of France in Washington D.C.
The authority forced upon theese characters also resonates with anti-absolutism ideas: the abuse of power by rulers was a general concern before the 1789 Revolution as well as an unease during the Bourbon Restoration and the July Monarchy.
Jean Valjean
I guess Jean Valjean serves the political views of Victor Hugo: when Les Misérables was published in 1862, he was a convicted republican (in exile in Guernsey, fleeing from Napoleon III) and was fighting against injustice (but somehow he always was: Le Dernier Jour d'un condamné [1829] greatly leans towards it). Jean Valjean symbolizes the everyday man but the roots of Les Misérables was Hugo's observations about inequalities and struggle against poverty and misery, claiming for respect and decency (which were reported during his Pair de la Nation's time and were posthumously published in Choses Vues [1887-1900]).
See also: "Les Combats de Victor Hugo" in Actes et Paroles, Paris, Bibliothèque Nationale de France [read on line].
Though Pierre Picaud was in an inspiration for Jean Valjean, Hugo could also have been inspired by Eugène-François Vidocq [1775-1857] who was a criminal turned a policeman / criminalist.
VIDOCQ Eugène-François, Mémoires de Vidocq, chef de la police de Sûreté, jusqu'en 1827, Paris, Tenon, 1828 [read on line].
See also, this article is about Vidocq but from Honoré de Balzac's perspective. Still, connections between literature and then living characters are drawn: BOUTERON Marcel, "En marge du Père Goriot. Balzac, Vidocq et Sanson", in Revue des Deux Mondes, january 1948 [read on line].
Edmond Dantès
Alexandre Dumas, also exiled in 1851, came back after Napoleon III's amnesty. However, Le Comte de Monte-Cristo was published between 1844 and 1846, so before Napoleon III's coup d'état. Edmond Dantès could reflect Dumas' personnal -conflicted- political convictions as well as Louis-Napoleon's relentlessness to take power.
This french article is about Dumas' republican engagement: RAHIER, François. Romantisme et politique : les batailles d’Alexandre Dumas, l’idée d’un théâtre républicain In : Le théâtre de Dumas père, entre héritage et renouvellement [read on line], Rennes, Presses universitaires de Rennes, 2018.
See also DUMAS Alexandre, "État civil du Comte de Monte-Cristo" in Le Comte de Monte-Cristo, Paris, La Pléiade, 1981.
Apparently, Dumas also drew inspiration from Pierre Picaud (or François Picaud) to shape Edmond Dantès: PEUCHET Jacques, Mémoires tirés des archives de la police de Paris, depuis Louis XIV jusqu'à nos jours, A. Levavasseur et cie, 1838 [read on line].
See also DUMAS Alexandre, "François Picaud" in Œuvres complètes de M. Alexandre Dumas, vol. 1 : Le Comte de Monte-Cristo, Paris, Le Siècle, 1846 [read on line].
Further readings
Now, about prisons and convictions in XIXth century french literature I would also recommend Honoré DE BALZAC, "Où mènent les mauvais chemins" in Splendeurs et misères des courtisanes [1846], and Eugène SUE, Les Mystères de Paris [1842-1843].
I gave further readings about prisons and prisonners in u/Many-Complaint-4191 thread: https://www.reddit.com/r/AskHistorians/comments/jm5j5c/prison_investigations_in_early_19th_century_france/gatshzc/