These sprites are formatted in the RPGM format. This means that the animations go 1, 2, 3, 2 (ping-pong) and the idle frame is the second frame. So, while there isn't technically an idle animation since it's a single frame, the pack means that there is an idle state for each character when it says that there is an idle animation.
I should note that the pack never said it had a run animation, just walk and attack.