All these are polygon and we will have more.
A single line cannot form a shape, it can only form a circle and a circle is not a class of polygon.
A polygon is a plane figure with at least three straight sides and angles, and typically three or more.
Polygon is a plane shape figure and we have different polygon
So, the only non-polygon that I think we can have is
1 sides, this cannot form a plane shape, then it is not a polygon.
2 sides, this cannot form a plane shape, then it is not a polygon. This cannot form any shape it will just form two lines intersecting each other