Most houses are developed with relatively even floors but slope over time because of sinking or sagging floor supports. Once the floor supports begin to sink, the floors can become sloped and uneven.
In homes with a crawlspace, the outside walls are supported on a continuous footing along the perimeter of the home and the inside walls are supported on footings and piers, which support beams, floor joists, and the subfloor. One or more of these building components can lead to uneven floors.
If you have sinking and uneven floors, your floor support is inadequate. The only reason things inside the living space of a home drop are because the supports underneath have dropped.
