Because of the broad nature of the question, the answer is both.
Without original thought and innovation in mechanical and electrical engineering, the technological advancements of this century (including the specimens that we're using to discuss this question) would have been impossible. But in that same vein of technology, many pieces of technology are based on an earlier, cruder piece of tech, the goal being to improve and upgrade the end product. So in terms of human inventions and technology, the answer is both.
i.e. making the bow and arrow out of a piece of wood and some stones is an original idea, but nowadays a bow and arrow is a complex machine made of pulleys and composite fibers (improvement on the original concept).
In terms of Literary, Religious or Philosophical thought, I think this idea of an original concept creating spinoffs can be used again. This disagrees with the OP's binary choice, do humans create an original idea every-time they think of something new? or are all ideas based from the a set of progenitor thoughts that seem to have existed for as long as humans have?
Many stories in the BIble, for example, have other similar stories that can be found in very different cultures than those of Judaism or Christianity.
I can only name one off the top of my head, but there are other similarities between various religions and christianity.
Noah's Ark
Not only is this classic tale of Noah and his floating zoo can be found also in the earliest recorded story known to man; The Epic of Gilgamesh.
Gilgamesh takes place in Ancient Mesopotamia (Current Iraq) and tells the story of super-strong hero Gilgamesh, an uncontrolled wildman who eventually finds civilization and starts adventuring. In his travels he encounters Utnapishtim, a man told by the gods to construct a raft in order to survive a great rain. Quite similar eh? I don't really know enough to make a conjecture on the topic, but the similarities speak for themselves; The Epic of Gilgamesh was written far earlier then The Bible was (and we're talking real, carbon dated numbers, not numbers in the Bible or any poo-poo like that, the breakdown is as follows
Gilgamesh is dated to about 2150-2000 BCE (Before Common Era, essentially BC), while the only source for Genesis being written is actually in the Bible, Moses wrote it in 1450 - 1410 B.C., the period between the Exodus and when the Jews found Israel.
That's over 500 years difference between the Biblical and Mesopotamian versions, so it sounds to me like the Biblical version is based on the Mesopotamian version.
A theory I read a while ago argued that Jesus was an analog for the Sun, and also the Egyptian God Horus, who was said to be born from a virgin and rose from the dead when killed.
Most explanations for these similarities are that these religious tales are spread by travelers and traders, and that people in other areas who heard those stories may have liked them, and either through fault of memory or tampering with them to fit into their own religion, these stories became another story (Like Noah and Utnapishtim)
However, I feel that Philosophy is a well-spring of original human thought. Philosophers by trade study other schools of thought and the writings of other Philosophers. Look at Socrates, Plato and Aristotle, the three have totally different conjectures in metaphysics which implies that they each had their own original idea. Original thought needs inspiration and purpose, like that which inspired the creation of Socialism and eventually Communism. In the 1800's the Industrial Revolution widened the gap between the rich and the poor ("The Gilded Age", as Mark Twain put it) to the point where some intellectuals like Robert Owen and Henri de Saint-Simon couldn't stomach the poverty of the working class. Their writings, along with Marx and Engel's Communist Manifesto where the beginning of Socialism and Communism, two totally new ideas in terms of Governmental systems. Look at America's government system, which is predicated upon the writings of Enlightenment thinkers like Rousseau and Locke.
John Locke himself believed that the Human was not born with any innate knowledge or ideas, but was a "Blank Slate" and that he got ideas from things he perceived around him. This idea supports both of my points here; that original ideas are based on either real world events or the need for an idea based on real people, and that original ideas can be tampered with and 'improved' in ways needed by various other thinkers.
Final example (for philosophical thought)
Industrial Revolution; workers are driven into poverty while Industrial barons reap immense profits
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Intellectuals schooled in Enlightenment thinking (every man is equal etc.) don't think this is just, slowly the concept of Socialism is formed
(de Saint-Simon, Engels)
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Communism (in the form of the Communist Manifesto) is created based on Socialism and Marx's own experience as a factory manager.
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Communist Revolution, Russia becomes the first Communist State
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Ayn Rand is born into Communist Russia, escapes to the US in 1926. Her books are based on her own unique philosophy, Objectivism
which is written in answer to the realities of the Communist-run State that was created from Russia. Objectivism emphasizes individual rights, Capitalism and self-righteousness in the face of mysticism and socialism.
Rand's philosophy, while it uses many ideas of American government, contains anti-Communist ideas crystallized and articulated in her books, Atlas Shrugged, The Fountainhead, and Anthem. (Read them, they're very good.)
But the Anti-Communist angle is based purely on Rand's thinking on Communism and her own experiences in Russia, seeing State officials wrest her father's soap store from him, his life's work, for the purpose of advancing the state, for example.
Ideas are created in response to a need, and ideas can also be revised to meet other needs as well.