The pack with the "Lesson 1" is the one to open. That card does in fact have a big "1" on it, it just ended up on the side that's not initially visible.
Spent 30 minutes looking for that big 1
Luckily I found it on the other side of the Lesson 1 card. Good to know I wasn't the only one.
ps. If you're going to check your tokens, there is also a printing error with those (One character is missing two, another has two extra). Check the forum if you want to know more).