The attitude that Shakespeare had toward collaborators, sources, actors and other writers seems best described as one of appreciation. It's clear that he recognized that what he was engaged in was part of a larger framework, both as a playwright working in Elizabethan/Jacobean London, and as a literary artist "for all time", to use Jonson's famous words, and that to be successful (as he was) would require working with and learning from other people. His level-headed attitude toward himself is also a model to learn from. A series of accomplishments of the magnitude that we're considering here doesn't happen without a disciplined and philosophically advanced self-image. In fact, it's interesting to think of him, on a personal level, in contrast with some of his most famous characters, Lear or Hamlet for example, who have trouble seeing themselves accurately. Harold Goddard concludes his very interesting essay in The Meaning of Shakespeare (1951) by calling Shakespeare "an unfallen Hamlet", after having explained that the prince, the character most approaching the capacity of Shakespeare, having to choose between force and art, fatally selects the former. It's purely conjecture, but it must be said that it's difficult to imagine Shakespeare ever having done the same.