You could put a burning torch in your backpack.
There were even times when you could put your horse in your backpack for later use. (Arena or Daggerfall, I think)

Sometimes people had millions of gold coins and no idea what to do with it.

There were no utensils in medieval times but there was Pepsi. Sorry, a movie about a RL game, but important nonetheless.

Bandits will always attack you no matter the odds. If you're a single weak person the bandit will attack. If you don't go that way and instead come back much later armed, armored and with 5 more heavily armed guys, then said bandit will still think it's a good idea to attack you.

Every medieval weapon can be mastered to perfection in a matter of hours, days at the most.

"Adventurer" was a legit job. A career choice for many.

And said rats and slimes would carry golden coins and other stuff that they dropped when they died.

- There were incredible accurate maps of most areas and regions. The exact spot where you have to go is pinned there.
- Every adventurer had a compass. And often a precise clock.

Nobody was able to solve the simplest problem. Instead they sent you on a "quest" to do the job. When you finished to catch the chickens for a peasant you could use this experience to get better in swordfight.

... and Dragons were likely to talk back. Initially, most complained about you disturbing their beauty sleep or something of the sort, but then the conversation either quickly turned interesting or was suddenly interrupted by angry roars and fireballs.

that enormous barrels could only hold a sprig of herbs and a beer or two

Simple locked wood chests or doors were either so strong that they could only be opened with keys or lockpicks and not by force, no matter how powerful your axe of total destruction was, or they were so weak that one could punch them open with ones bare fists.
Skills only worked when they matched or exceeded the required level but then they always worked perfectly. Luck or probabilities weren't known back then.

Unlike today VIPs were immortal. Near them you either could not draw your sword or your attacks went right through them.

And the #1 fact:

You couldn't venture forth without gathering your party.

There was no day and night- cycle in some regions. Only constant day.
You did not need any sleep, except when you were seriously hurt. Then you completely healed after resting.
Some weapons and clothes had strenght requirements. When you didn´t meet them, you could not even hold your equipment in your hands.

But while you couldn't actually use the sword because you weren't strong enough, you could carry it in your backpack no problem...