He Died Before the Plays Were Written
Shakespeare was undoubtedly influenced by Marlowe. Marlowe conceived the theatrical tragedy, a genre that Shakespeare would go on to develop. However, Marlowe died before the first Shakespeare play was published, therefore ruling him out of the authorship debate.
There is no documentary evidence to suggest his death was faked. In an inquest, sixteen jurors concluded that Marlowe died in 1593.
If he faked his death as proponents claim, and continued writing plays and publishing them in Shakespeare's name, why would he not reveal himself once the plays became a success?
Every Playwright at the Time Dealt With Similar Themes
Many plays written around this time bear strong similarities. Each writer was basing their work on a small subset of source materials rooted in religious texts, mythology and history. There is bound to be significant overlap in themes, characters and structure.
While Marlowe and Shakespeare's work contain similarities, there are clear differences between their writing styles, particularly when writing comedies.