hd_scania
To what @rvp already said, I'll add you ought to make sure not .conf file in xorg.conf.d contains any InputDevice section pointing to either 'mouse'/'synaptics' (from xf86-input_mouse/xf86-input-synaptics) as Driver, or '/dev/sysmouse' (the virtualized pointer for user processes to use, which relies on moused) as Device. For libinput to work with keyboard/touchpad, you need something like:
Section "InputClass"
Identifier "libinput keyboard catchall"
MatchIsKeyboard "on"
MatchDevicePath "/dev/input/event*"
Driver "libinput"
Option "XkbRules" "evdev"
EndSection
Section "InputClass"
Identifier "libinput touchpad catchall"
MatchIsTouchpad "on"
MatchDevicePath "/dev/input/event*"
Driver "libinput"
Option "MiddleEmulation" "on"
Option "DisableWhileTyping" "off"
EndSection
a proper standardconfig already comes with the libinput package itself, and is included in the xorg meta-package