I'm thinking a way to break somebody down and then building them back up is to have no characters start with inspiration, but get them when they find trinkets representing their unit in the dungeon.
At best you're always at Exhaustion Level 1. Water management is as important as Rest management. The 'nerd' will be forced to be the heavy weapons expert. The athlete will be forced to focus on intellectual stuff.
Have you been to boot camp? Besides the yelling and not being able to do anything right, it was boring and monotonous. I would not recommend it for a game. You could do something on teamwork to run the new group through some paces and see how they react to certain situations. Some examples may include:
A narrow hallway of bridge where they fight one or two wide.
A temple with undead
A trapped room filling with water and crocodiles.
How not to get in a line for lightning bolt attacks.
Something like a solo fight, a simple exploration challenge with a reward like a key or code for use at next exploration, a small group fight, a short rest that they must make safe, a small group fight, an exploration challenge that requires teamwork, a boss.
Make major fails on the exploration give exhaustion, but they advance. Seriously.
Emphasize teamwork after those first two elements.
"The Dungeon" should have renewable enemies: Things that can very easily be replaced.
Perhaps you keep undead. After those were slain, they can be raised again? Perhaps you have oozes that just ooze themselves back together after they were slain? Or an animated armor that is re-animated after it's been violently disassembled? Obviously, these monsters must be adjusted to a level-1 setting.
Add a few illusions on top, and you get a decent newbie dungeon that gives the players a real challenge, and yet feels like something that a family keeps in their basement.
Dungeon Magazine has a few 'Challenge of the Champions' series that had traps and puzzles you can pirate for your needs.
To learn to be first level may need to be more player faced than PC faced. Some think that 1st level PCs are already well-trained and local heroes to start with- a step above the common folk.