No an idea doesn't need to be unique to be valuable, it just needs to fulfill a meaningful need which isn't currently being catered for.

A great book with very useful examples to read is "Blue Ocean Strategy".

Innovation can fall into two camps. The first where companies innovate and improve within an existing category, or, the second where companies create a brand new category of product.

An example of the later would be a Facebook....

An example of where a company innovates and improves on an existing product could Nintendo when they launched the Nintendo Wii in 2006.

This new console focused on value innovation where they reduce the cost but also differentiated the product doing away with the DVD/cartridge element most consoles had at the time and introducing a wireless controller.

Another example is Yellow tail, the wine company who instead of focusing on prestigious traditional branding focused on mass market appeal making a sweeter wine to capture demand from beer and spirit drinkers, creating a very simple range making it simple to buy, a red and a white.

The last example is Cirque du Soleil who moved away from animal acts to reduce their cost based and focused on a more theatrical proposition inspired by the world of theatre with productions never see before.

The result for these companies? They created new market space in existing and sometimes very cut throat markets.

So you don't have to be a Facebook to be successful, you "just" need to offer customers something meaningful and differentiated.

A fun exercise for companies can be to look at how certain companies have looked outside of their verticals to innovate and come up with great ideas and winning strategies.

Good luck!