While a common isekai trope is to bring in someone from the real world into a video game-based world, this manga subverts that trope by bringing into a real fantasy world someone whose view is video-game based.
Mabel's lazy/reluctant nature is played for laughs, but consider that heavy winter/cold weather requires people to use as little resources as possible, or alternately to use resources carefully. A low threshold for extended labor is somewhat expected for a cold-related person.
Her being all-powerful means she doesn't need to be careful with resources, she's just too lazy to go all out.
Uncle singleminded focus to return home while ignoring most of the niceties in Granbahamal is easy to understand given the shitty life he lead there. His first experience with people there got him beaten to near death and he would've been beheaded if he hadn't used his New Life in Another World Bonus to talk in their language, all this at the ripe age of 17. Even later there are numerous times Uncle mentions being chased and attacked in his sleep and every village tries to kill him due to his looks.
The Uncle looks like a relatively ordinary 17-year-old boy when he first reaches Granbahamal until he gets beat up, chained, accused of being an orc variant, sold for 3 bronze coins at a freak show, jailed, and then left to rot because his jailer forgot about him. That led to him aging prematurely in his physical form from teenager to 40-50 year old man. It's also why he looks the same at 20 years old and at 35-36 years old.
