Photo from page one of this discussion.
This is a nice wall display above and around a fireplace. The old snow shoes, the candles in the fireplace, the lantern in front of it and the decor are all comfortable. The BP rifle with the strap hanging down in front of the fireplace. Armored farmer noted that he changed the original pic to this one because the wanted to replace a bulb in the ceiling fan. The other pics of modern fireplaces show electric lights, painted walls comfortable chairs, etc. I'd sit in any of them and read a book or watch the Super Bowl. We might get some beers from the fridge and snacks we could order some pizza and have a nice time.
But...
"Why is it that guns are commonly stored over the fireplace? Was it to keep them away from the kids? I would imagine warm dry air would help keep the powder dry as well, but in the historic old world it seems much more reasonable that a need might arise and the gun would be more accessible near the door of the cabin. Predators after the livestock, Indian attack, target of opportunity comes strolling by and looks tasty... So is the gun over the fireplace a historically correct thing or is it a Hollywood thing?"
This is a question from the op seems to be not so much about now but about the frontier. It's a custom today to have an heirloom rifle over the fireplace. It's a part of the decor and display.
Have any of us been to a home where a person had their ARs in 300 Blackout and .223 above the fireplace? Or the Model 70 in .270 Win with the Leopold scope hanging there next to the Benelli shotgun, next to the Ranch Rifle and the Marlin with the laminated stock in 45-70. Not so much I don't think not above a regularly working fireplace that's needed to keep the place warm or to cook supper in.
In frontier homes folks cooked in their hearths which were larger. No ceiling fans, unless there was a hole in the roof. There may have been iron frying pans above the fireplace and copper pots but not so common to find a working rifle there.
I gotta add this...I don't suppose it was that common in the in teh houses of the working people from the 1600's to the 20th century for working rifles to be placed above hearths where folks cooked, used fires for warmth, etc. It was more common I know for a fact to see it in the homes of the well to do and the wealthy.