What would a 3 dimensional being appear as in a 2 dimensional world.
Take a cube as a simple example. In a 2 dimensional reality it would appear to be a square. So 2 dimensional beings would perceive a cross sectional area of the cube, which appeared to be like themselves. They would therefore only be aware of a very small section of it's true being.
You're right, and that's why we're only aware of a very small section of the next dimension. It gets interesting when trying to imagine being in the 4th dimension visualizing the 5th and so on. (sorry for the long video, I know that's like a week on the internets..)