Evidence 1: In spooky month 1, It moved when Skid and Pump summoned Moloch, possibly trying to save the kids from what's going to happen in spooky month 3.

Evidence 2: In spooky month 4, it fell on top of the Happy Fella, Giving Lila, Skid and Pump enough time to run, You could say it fell over because the board knocked it over, however the overall event seemed unnatural in the pause way it fell over.

Evidence 3: In spooky month 5, It appeared in front of Bob, Blocking his path to Lila

Skid's dad could have possessed the mannequin after dying long ago and did all the stuff mentioned previously to save his family.

P.S.

At the end of spooky month 5, When Lila see's bob in the picture, it could possibly be hinting that back then, Bob and Lila had a deeper history, You can tell it's bob because of the pictures at the very beginning match that of the man in the photo, Skid also says "Mom, did you know...…Him?" because Skid knows that Lila knew their dad, he's obviously referring to someone else.