If you consider only 2-body system, you can not prove it.
The motion is relevant. From your standpoint, Sun is rotating around Earth. From Sun's standpoint, Earth is rotating around Sun. Both views are equally true.
If the sun rotated around us, then it would be the same height in the sky year-round since it would have a more fixed path. But it's not. It gets higher in the sky in summer and lower in fall.