XCB is actually lower level than xlib, in that sense it is more directly using X11 because unlike xlib it only really implements the client protocol and wraps i

XCB is actually lower level than xlib, in that sense it is more directly using X11 because unlike xlib it only really implements the client protocol and wraps it up into an interface. I was however planning on trying out Xlib anyway on my path of exploration from simplest/lowest level to complex/higher level libraries: fbdev, DRM < DirectFB, libdrm < XCB < Xlib < SDL et al.