The fact that one's original ideas tend to get discovered and products appear along the line of thinking of these ideas soon after you have them is because your line of thinking was logical to follow. Needs emerge in culture and then solutions follow to fill the needs. My father used to ask me this very question when his inventions would appear in the stores some time after he had them.
A secret to making an invention is to see a need before anyone else does. Of course, having something that provides this need ready to sell before anyone else has thought of it is key. The other secret is that inventions are logical in hindsight, but often not in foresight. To arrive at an invention, one needs to think laterally. Literally that word means, "sideways thinking," but it also means using a lateral thinking skill because doing so will open up possible alternatives.
Sometimes, it's a matter of design. All the elements are there and nobody has thought to combine them in the unique way that you imagined. Whole genres of businesses have been put together with just this one ability to design a way through a problem that stops other people.
Another sort of invention is the resourceful impromptu of using something uniquely similar to fulfill a need. Of course, one thing that serves a certain purpose can be commandeered to serve a new purpose that you imagine it could have if it were slightly modified or combined with something else.
A good example is being in a hotel room without an iron that also has a kitchen. Heating up an iron pan and inserting it into a paper bag serves as a substitute for an iron. But so does steaming the wrinkles out of one's clothes in the bath or by spritzing one's clothes with water by flicking your wet toothbrush. In that case, redefining what it is you actually need from "iron" to "wrinkles gone" helped you imagine a different solution.
Really, anyone can have an idea. To be able to find ways to make the idea real, that is the test of it. If you know about sites such as www.kickstarter.com - it's not so hard to get a great idea launched anymore. The creative person who coined the word for "lateral" thinking came up with a new word: operacy. Similar to literacy and numeracy, operacy means the ability to make stuff happen. It's a more basic skill that should be learned that's even more important than how to have original ideas.
