A species of assassin bug I believe. That could indicate an infestation of some other type of bug (insects, centipedes, arthropods, etc.) as it does not appear to be a kissing bug (blood sucking parasitic species) which is in the same family because those are dark brown / black in color.
Like you said, relatively harmless.
HTH
EDIT: After a bit of nosing around, That appears to be a predatory adult and like praying mantis, they are considered beneficial.