William Shakespeare Deposition in Mountjoy V. Belott 1612
As being too pedestrian to write such brilliant works.  The lack of background to explain the deep insights into lifestyles he'd have had little or no personal experience with seems to imply an impossibly creative instrument. However, there is another explanation.
Something in his real life must have inspired and informed his work because nothing comes from nothing and something must come from something. I have the answer. Insider knowledge passed down through my namesake. How about a family of French refugees? An old noble clan of Huguenots fleeing the chaos of civil unrest after a decade of war with the Catholic majority... a shadow of the French Revolution to come. A saucy affair in a time when ladies of the house provided... "services" to the upper crust.
"War began in 1562 when a number of Huguenots were massacred by the Guises in a church at Vassy. The Huguenots were only a twentieth of the total French population, yet fought so fiercely they were able to win concessions from the Roman Catholic majority. In 1572 a peace was arranged." - https://www.christianity.com/church/church-history/timeline/1501-1600/huguenots-driven-out-of-france-11630022.html
The Mountjoys were loud, rich, and respected if slightly diminished from our glory days in France. A family with significant history. Though the name was enjoying a resurgence of fame at that time. While Shakespeare was writing Hamlet, Charles Blount, Lord Mountjoy was "civilizing" Catholic Ireland for the English Protestants. The London Mountjoys had a working connection to the aristocracy at that time in ways Shakespeare admired with great interest.
He wrote most of his plays while living in Mountjoy House on Silver Street. From 1594, (Romeo and Juliet) as an occasional house guest while working the big city and then 1602 until l609 ( Henry V, Othello, King Lear, Macbeth, and Anthony and Cleopatra) as a resident border; the Bard, lived with Christopher Mountjoy and his amorous wife, Marie (my great, great, great, great....you get the picture). His last sole-written play was The Tempest in 1610. Shakespeare is believed to have retired from writing altogether in 1613. Five years after leaving London he died on April 23, 1616 aged 52 in New Place, Stratford-upon-Avon probably of alcohol induced fever.
James Shapiro, in his book The Year of Lear: Shakespeare in 1606, suggests that Shakespeare moved to Mountjoy House from across the river in Southwark because of recurring plague outbreaks, and that his subsequent departure was prompted by Marie Mountjoy's death in 1609 likely from the same cause.
"What Shakespeare thought of the woman who had entreated and solicited him and why he abandoned Silver Street so soon after her death...must remain a mystery" - The Year of Lear: Shakespeare in 1606 (New York: Simon & Schuster, 2015), 286–287.
Was the untimely demise of my (great, great, great)-grandmother related to the tragic destiny of Cleopatra in his finished work in October later that year? Scholars seem to think so. There are in fact several notable references to Mountjoy in Shakespeare's works so there is clear precedent.
It is suggested that Shakespeare used his experience of living with a family who all spoke French for use in his plays. For example, the scene in Henry V between King Henry (which was written before and around 1600) and his future bride, Katherine, the daughter of the French King, with her maid acting as interpreter.
HENRY: Madam my interpreter, what says she?
ALICE: Dat it is not be de fashion pour les ladies of France,–I cannot tell vat is baiser en Anglish.
HENRY: To kiss.
ALICE: Your majesty entendre bettre que moi.
HENRY: It is not a fashion for the maids in France to kiss before they are married, would she say?
ALICE: Oui, vraiment.
There is also a small part for a French herald called Mountjoy, which it is speculated, Shakespeare named after his French landlord.
So whenever Shakespeare sat down by the fire after a hard day at the Theatre, hoping to knock off a few more pages of Macbeth, he would frequently be disturbed by Mountjoy begging him to use his skill with words to persuade Belott to propose to Mary (Christopher Mountjoy's daughter and only child...not unlike Juliet.). "Knock, knock, knock! Who's there, i' the name of Beelzebub?" may well have been inspired by the persistent Mountjoy. 
In 1604 Mary Mountjoy and Stephen Belott were married and in 1612, Shakespeare was a witness in a dispute involving the very same. His deposition (a print is provided above) includes the earliest known instance of his signature the others being his final wills.
"Scholars have interpreted information from Bellott v. Mountjoy in various ways. Some see a connection between Shakespeare's residency with the Mountjoys and his interest in "problem comedies," pointing particularly to As You Like It, Measure for Measure, All's Well, and Pericles."  I'd suggest that Shakespeare and Mountjoy met around 1594 while "Comedy Of Errors" was playing. Probably because Christopher's  wig making business as he was a "tirer", a maker of fine head dresses, gave him regular access to theatre people where he could naturally advertise his rent-able rooms to those passing through.
In fact, Queen Anne, wife of James I, was one of their customers.... The words 'Oh for one Mr Shakespeare that laye in the house...' leapt out of the bundle of old court documents dating from the year 1612.
This point about Christopher being a "tirer" is very important to my theory of the Mountjoy experience being a much larger part of the story than traditionally realized. I think his friends knew there was some connection between his work and his home life. He was extremely private and yet put out large volumes of product on subjects he shouldn't know. Dwarfing his contemporaries...and he did almost all of it working in his little room at Mountjoy House surrounded by a lively French family of has-been well-to-does, who's tiring shop was below their living quarters.
So they all spent a lot of their time together. During the day a wealth of noble ladies and lords, including Queen Anne, would float through dropping stories, and gossip, and snooty terms and specialized humour...in other words source content... for over a decade during the prime years of Shakespeare's best work. How many times had Christopher waved rent along the way. You might say the Mountjoy's were early investors in the bard's yet unrealized potential.
Upon William's death his friend, James Mabbe, said "We wondered, Shakespeare, that though went'st so soon/From the world's stage to the grave's tiring room."  Coincidence? Or an indication that among his fellows it was no secret where he got his material. We've always assumed he meant the dressing room at the Globe Theatre...but perhaps he meant the tiring shop above which he'd lived with the Mountjoys during the most productive years of his career. I say he was not a fraud. He wrote it all. It can now finally all be explained by simply exploring what little we actually know about the bard's real life.
So let's go deeper. Shakespeare writes Romeo and Juliet between 1594–1597 with final version in 1599. Let's try to give a new answer to a very old question. Why'd they hate each other? A story driven entirely by an ancient grudge between two French families in a foreign land. Capulet and...Montague? Strange names. Why is Juliet an only child who once had siblings who have since died. Why is Juliet a Capulet rather than Montague?
Now this is pure speculation for fun but this is what I think might have happened. In 1594, Christopher and William both liked to drink and they became friendly. William is amused to hear Christopher is a Mountjoy especially given the political climate at the time heavily revolved around the activity of (Charles Blount) Lord Mountjoy's Campaign in Ireland.
Baron Charles Blount, served as Lord Deputy of Ireland under Queen Elizabeth I, then as Lord Lieutenant of Ireland under King James I. 
Maybe Shakespeare talks about a play he's working on called Romeo and Juliet based on a work by Arthur Brooke, 1562. That he's struggling to drive the story. He talks a bit about Capulets and Lord Montague disliking each other, but why? And Christopher says in a thick French accent. Monfrague?
Christopher volunteers exaggerated stories of the Mountjoy namesake's glorious past. Talks about the "ancient" grudge between the Order of Mountjoy  and the Order of Monfrague over land and title circa 1180 during the crusades. The Monfragues being once Mountjoys dissenting from joining with other Orders to form the Knights Templar. Two powerful French "families/orders" in a foreign land. In real life, Spain, in the play, Italy. In 1180 there wasn't much daylight between the two. In 1221 they were forced together again by circumstance beyond them both and ultimately both are gone. Small players on a big stage with forces that move them like pawns.
Shakespeare is inspired by these stories and Christopher tells Shakespeare about his room for rent and his family. Talks about his only child Mary and how her siblings have died from plague and unavoidable tragedy befalling people doing the most natural things. Love and war. The dark comedy. Wouldn't it be funny if William wrote a play like that. A little bit of Mountjoy and a lot of Brooke  explains it pretty well...don't you agree?
 Kinney, Arthur F., editor. The Oxford Handbook Of Shakespeare. Oxford University Press. 2012. ISBN 9780199566105. Page 11. Verse by James Mabbe printed in the First Folio.