An football is approximely a two-sphere. From a rougly point of view, our notion of an "3D object" is in fact treating surfaces of two dimensions on our "natural" 3D life. However, can we say that an football is in fact a 2D object? The football are an 3D object or not?
The motivation for this question is: A sphere on a 3D space is a curved surface of two dimensions and the representation is possible because we are able to access 3D space, naturally. But, if we attempt to draw some 3D curved surface (3-sphere), we would need some 4D space for it. My point is: An 2-sphere is an 2D object and an 3-sphere is a 3D object but our 3D football is in fact and 2D surface then is an 2D object. Following this logic, all the things (buildings, chairs,etc..) are just 2D objects and we call then "3D objects" just by our possibility to access 3 dimensions.
A football is a 3D object. It has a thickness as well as its two surface dimensions. The surface of a football is an imagined 2D surface that is not actually a physical object. The fact that the thickness of a football is much smaller than its surface dimensions makes a football "approximately 2D" in a sense.
Other objects in everyday life are not necessarily even approximately 2D. For instance a billiard ball is not hollow like a football. Thus it is 3D.