Robinson Crusoe was inspired, as is well known, by the travails of Alexander Selkirk, marooned on the island of Más Atierra in the Pacific Juan Fernandez group in 1704. Selkirk got into an argument with the captain of his ship and it was decided, it seems by mutual agreement, that it might be best just to stop and let him off. He survived on the island for four years, and on his return to civilization his story became famous. Defoe took what was already a very well known story and raised it from the plane of the famous to the plane of the immortal.
But this doesn’t explain the title. The actual name ‘Crusoe’ very probably came from Timothy Cruso, a schoolfellow of Defoe’s and a friend in later life. Cruso, like Defoe, was a Dissenter: in fact he was a dissenting minister in the church of the Crutched Friars, London, and the author of God the Guide of Youth (1695). Members of the Dissenting or Nonconforming churches (ie Christian believers without the Anglican faith) were denied a university education or a civil or military career. The History of Dissenters gives a short character-sketch of Cruso:
While his popular talents were crowned with great success, his amiable disposition and conduct endeared him not only to his own family but also to a very large circle of valuable friends. But the heavenly treasure was deposited in an earthen vessel, and his soul, like that of Watts, perhaps also of Paul, and some other distinguished men, was not well lodged; for his body was contemptible in its appearance, and frail in its texture. Exhausted therefore by the constant studies and hard labour which his indefatigable mind, ever eager to increase both his knowledge and his usefulness, imposed upon the feeble frame, he sunk under his work in the prime of life, and died on the twenty-sixth day of November, in the year one thousand six hundred and ninety-seven, when only forty-one years of age.
Robinson Crusoe is of course a highly theological work, representing one man’s dialogue with the Almighty shorn of any institutional trappings, a tale of survival through personal resourcefulness and faith. There a strong dissenting theme, therefore, in Robinson Crusoe. It seems very likely that Defoe’s use of his friend’s name was intended not only as a personal tribute but as a codified sign of support for Nonconformism.
Bogue, David, and Bennett, James: History of Dissenters, from the Revolution in 1688, to the Year 1808 (1809)
Backscheider, Paula R: Daniel Defoe: His Life (1992)