For the record, I think 'The Mummy's problems are probably down to it being made by a committee, far more than even other films out there this year.
A movie like this, intended to launch, not just one franchise, but a franchise of franchises, and starring two very expensive actors, is going to be subject to enormous amounts of "help" from everyone at Universal with an office and a job title to protect.
We all know that a lot of the big movies are not made in the traditional "write - shoot - edit" order necessary for lower budgeted films. Instead they design and storyboard, THEN write, shoot, rewrite while shooting, reshoot, rewrite some more, reshoot some more, edit and reshoot, create VFX and reshoot and re-edit and rewrite some more and reshoot and loop and redo some VFX and then finally assemble the pieces as best they can and release the end result.
It's a miracle any of these movies work.