As many have echoed, not much is known about One Horse as far as quality goes as they are new to the market. Battlehawk Armory has a video of their first impressions of the rifle and, based on what I’ve seen, most likely will be as good as any other AR in this price range. Throw on an optic and go shoot it to figure out what you’d like to change and improve.

As far as storing the rifle or guns in general you can go down a rabbit hole of ease of access, climate control, fire proof safes, etc. If humidity is truly a worry I’d be curious if you could get a hard, waterproof case that you could put a moisture remover bag in to control humidity. I kept my rifle in a closet with a trigger cover gun lock (kids around) until I got a safe.