I mean, I have a friend and he is working as a developer. He can do a daily simple CRUD. But he can't solve a "print a 90 degree triagle" problem :/
For further actions, you may consider blocking this person and/or reporting abuse
Problem solving is totally a learnable skill, like most things.
It's often what separates a developer from another one. The amount of problems you have solved in the past and the toolbox you have at your disposal.
I don't think there's anything magic or arcane to it.
The thing is, not everybody needs to solve the same problems. "Print a 90 degree triangle" is a valuable problem to solve but as you probably noticed, might be useless for your friend's job (or just not needed yet).
As @rhymes already noted, context makes a big difference. What might be a vital skill for one person might be nothing more than a parlour trick for someone else.
As to 'simple CRUD': despite appearances, it often takes a lot of skill to make (and keep) things simple.