Does a thematic map only display those things to the visible eye

No, a thematic map doesn't only display those things that are visible to the eye.

Explanation:

A thematic map serves the special purpose of displaying the particular regions in various highlights of different hues and shades in order to specify the information of the theme on which the map is based. For example, if the theme of the map is 'the regions affected by global warming', then only such regions will be highlighted in the map with different shades of colors for different intensities of the effect of global warming on the region. In such a map, we know that 'global warming' is not something which is visible to the eyes.

A thematic map is designed to show distribution of human or natural features or data. Example:population