The original poster was much more apt than your explanation. CMOS sensors in modern cameras actually have arrangements exactly like that on a pixel level. They use filters for each pixel, doubling up on green. With something like this you might be able to combine the filter and the lens.
Your explanation of 'thousands of frequencies' is somewhere between misleading and incorrect. Electromagnetic radiation is a continuous frequency. Our eyes' 'sensors' are not sensitive to exact wavelengths of course, they are sensitive to a range. Some more sensitive to red, falling off into orange, into yellow, into green (as the frequency of light goes up). We are most sensitive to colors in the green spectrum, least sensitive to blue.
Do you know why the sky is blue? It is because of the spacing of ozone particles. It absorbs and reflects higher and lower wavelengths _more_ but red and green light still make it through, as well as UV radiation.
