Why do superheroes always know what they have to do? What if they're simply clueless kids?

A mighty wizard has captured the seven deadly sins and has been keeping them. However, he is growing old and needs to hand over his powers to a replacement to control the sins. He is a little too late, and someone unworthy takes hold of the powers of the sins.

At last, he makes Billy his descendant without much instruction who as a kid tries to get used to the superhero life. There is a comical twist. He turns into an adult when he wants to use his powers and can also turn back. He just needs to say Shazam.

This leads to some comical scenes of a clueless kid getting to know a special life. Of course all of this until the supervillain starts chasing after him...

It was from time to time entertaining but on the other hand it was also pretty generic and boring. The villain was just super generic without a real threat or meaningless objectives and Shazam's powers are also super generic. It is also so illogical. The wizard spent years searching for the worthy, and then he just randomly gives his powers to Billy without testing him and without giving him any instructions. And then Billy just randomly gives powers to 5 more kids without any testing and didn't lose his own.

And then there is so much else that is so weird. But I'm not going to go on with it. So yeah, it was entertaining at the beginning but not really a good superhero movie.