A picaresque novel is one that is a reaction and counterpart to works that revolved around knights and strict adherence to the code of chivalry. Typically, a picaresque work concerns a protagonist of flexible and situational morality that uses their wits to overcome adversity. These heroes did not put a value on hard work and doing things the "right" way, and operated with a method that was based on results rather than on virtue.

While Crusoe certainly seems to be of a gray morality in hindsight, he could hardly be considered to be a picaresque hero of his time. First and foremost, picaresque heroes are almost always shown to come from very meager means, as it is a desire for often myopic financial gain that typically motivates them. Crusoe leaves a very comfortable life to go adventuring just for the sake of adventure, a prospect that heroes of the picaresque sentiment would no doubt find foolish, naive, and futile.

Crusoe's relationship with Christianity further disqualifies him from falling into the category of the picaresque. Typically, in a picaresque work, religion is adhered to only for societal and social reasons. Consider Mark Twain's Huck Finn, who is considered to be one of the foremost picaresque heroes. When learning about religious figures, he states that he was originally excited, but lost interest when he found out that Moses was dead, because he "took no stock in dead people." Picaresque heroes often portray religion in sardonic or sarcastic terms such as this, and would scarcely have a non-performative interest in matters of the spirit.

Ironically, Crusoe turns to God when he is cast away on an island, the only time that we can be 100% certain that the act is not performative. This genuine interest in the divine makes Crusoe's status as a picaresque character dubious enough, but he takes it a step further by beginning to evangelize to Friday and other "savages" that he meets. In moments such as these, Crusoe could not seem farther from the picaresque trope.

To a certain extent it is. Robinson Crusoe tells the tale of a roguish character who embarks on a series of colorful adventures, during which he often defies the values of civilized society, relying instead upon his wits to survive.

Crusoe's roguish manner is shown in a number of different ways. First of all, he sets off on his epic adventures against the express wishes of his father. At a time when fathers were expected to rule their families with a rod of iron this would've been considered nothing short of scandalous. Then there's the matter of Crusoe's dealing in slaves. Although slave-trading was perfectly legal in those days, it still had a disreputable air about it. It was not thought to be an appropriate activity for a self-respecting gentleman; only rogues and low-lives were generally held to be involved in this morally dubious trade.

Nevertheless, Crusoe eventually sees the error of his ways and experiences a religious conversion while stranded on his desert island. This is one notable departure from the genre of the picaresque novel. One certainly can't imagine someone like Moll Flanders, another of Defoe's great literary creations, undergoing such a complete transformation.

While Robinson Crusoe shares elements of the picaresque novel in that it is a first-person narrative that depicts a character living by his wits, it is not, in the end, of that genre. A picaresque character lives in and interacts with his society, and these interactions are often satiric, pointing out problems and vices in the larger culture. The hero often is the victim of cartoonish violence or caught in exaggerated situations.  In contrast, Robinson Crusoe is almost always alone on his deserted island, first with animals and much later with Friday as his only companion, and his situation and survival are always realistically portrayed. While the novel is not without satiric moments, especially when Crusoe and Friday finally get to Europe, this book is largely an earnest account of one man's resourceful struggle to survive. 

Further, a picaresque novel is usually a loose collection of somewhat disconnected episodes, whereas Crusoe has a tight trajectory of shipwreck, survival, and deliverance that unfolds as a whole. Finally, characters in a picaresque novel tend not to change, whereas Crusoe experiences growth, particularly in religious faith, as he survives on his island and has time to reflect on providence. 

Very interesting question. The earliest novels were called picaresque in that they involved a roguish main character who travelled widely, survived by means of their wits alone, and preyed on those less clever than themselves. These novels contrast the idea of chivalry with the idea of pursuing adventure for its own sake. They were also episodic, which meant that they were based around a series of single episodes which had no relation to the rest of the action in the book (kind of like when you miss an episode of Friends it doesn't really matter to the overall plot of the show). Lazarillo de Tormes and Don Quixote are examples of picaresque novels.

Based on this definition, therefore, Robinson Crusoe doesn't really seem to have all the elements of a picaresque novel. It does focus on one man's experience, but we can hardly describe him as a rogue, and though he does survive by his wits and skill, he does not take advantage of Man Friday in any devious fashion. Also, it is not episodic - there is a clear plot that runs throughout the story. It therefore can be said to represent the development of the novel from picaresque into something more interesting.