You’ve likely just incorrectly referenced the humanoid.
OK, I tested this model on an empty game, then promptly deleted it. See below.
This model has an R6 rig which seems to work fine. Make sure you are using R6 animations, not R15. Try disabling the Animate script. That interferes with NPC animations. If that’s the problem, your animations may have an idle or core priority (overwritten by everything else).
It also has a bunch of other scripts and unusual behavior. For example, after deleting the scripts and renaming the model, the game spawns 2 copies with the original name and one of those copies kills the original. I didn’t do a whole lot of investigating after this. No obvious script was running.
I deleted all the scripts and everything works fine, except the animation