The answer to the question depends upon what exactly should be called as "graphics primitive". In this answerthis answer from the practical point of view I define it as a container which can be found inside of Graphics or Graphics3D, which draws something and is not a graphical directive or Dynamic wrapper. This definition differs from the usual meaning but covers all the key cases. Here is (I hope) complete list of such containers for version 10.2:
{Point, PointBox, Line, LineBox, Arrow, ArrowBox, Rectangle, RectangleBox, Parallelogram, Triangle, JoinedCurve, JoinedCurveBox, FilledCurve, FilledCurveBox, StadiumShape, DiskSegment, Annulus, BezierCurve, BezierCurveBox, BSplineCurve, BSplineCurveBox, BSplineSurface, BSplineSurface3DBox, SphericalShell, CapsuleShape, Raster, RasterBox, Raster3D, Raster3DBox, Polygon, PolygonBox, RegularPolygon, Disk, DiskBox, Circle, CircleBox, Sphere, SphereBox, Ball, Ellipsoid, Cylinder, CylinderBox, Tetrahedron, TetrahedronBox, Cuboid, CuboidBox, Parallelepiped, Hexahedron, HexahedronBox, Prism, PrismBox, Pyramid, PyramidBox, Simplex, ConicHullRegion, ConicHullRegionBox, Hyperplane, HalfSpace, AffineHalfSpace, AffineSpace, ConicHullRegion3DBox, Cone, ConeBox, InfiniteLine, InfinitePlane, HalfLine, InfinitePlane, HalfPlane, Tube, TubeBox, GraphicsComplex, GraphicsComplexBox, GraphicsGroup, GraphicsGroupBox, GeoGraphics, Graphics, GraphicsBox, Graphics3D, Graphics3DBox, MeshRegion, BoundaryMeshRegion, GeometricTransformation, GeometricTransformationBox, Rotate, Translate, Scale, SurfaceGraphics, Text, TextBox, Inset, InsetBox, Inset3DBox, Panel, PanelBox, Legended, Placed, LineLegend, Texture}
