Wasn't there last weekend but I've been to Waverly twice, once in 2019 and again in 2021. The shadow figure thing keeps coming up in reports from that site and it's worth taking seriously just because of the sheer volume of independent accounts that describe the same basic shape and behaviour - tall, moves along the corridor wall, doesn't respond to direct torchlight.
What I'd want to know before jumping to conclusions is what the lighting conditions were like. That building has some genuinely weird internal geometry and the way ambient light filters through the broken windows at certain times can produce some convincing shadow artefacts. Not saying that's definitely what it is, just that it needs ruling out first.
If multiple people in your group saw it simultaneously and from different positions that's more interesting to me than a single observer. Did anyone get footage? Even shaky phone video is worth posting up. Would be good to compare against previous sightings documented on here.