The problem with The Meg isn't that it's dumb, it's that it isn't dumb enough. This is a movie about Jason Statham fighting a giant prehistoric shark that eats submarines, which isn't the sort of material that demands the My Dinner With Andre treatment (although I would watch that). All a super-shark chomp-em-up like this needs is a series of increasingly improbable chompings and a cast willing to gnaw more scenery than their ravenous, doll-eyed counterparts. Deep Blue Sea got this formula pretty close to right 19 years ago, but The Meg (which, incidentally, languished in production hell for about the same length of time) hasn't learned much from history.
Director Jon Turteltaub employs the same quippy hangout vibe he used to good effect in the the perfectly fine National Treasure movies, but those films had a lot of scenery changes and wacky hijinks to quip at; The Meg has conspicuously few sets and hardly any hijinks. And honestly, there's only so many quips you can make a the expense of an enormous shark (nature's perfect killing machine), especially once it starts eating your friends. Everyone in The Meg is just too... chill, and that damningly includes the titular shark, who spends way too much of the movie swimming in conspicuous circles.
And the premise is perfectly serviceable! Statham plays a disgraced deep sea submarine rescuer called in for one last job to rescue his submarine pilot ex-wife (Jessica McNamee) from the secret lair of a giant shark that, frankly, humanity should have left well enough alone. And The Meg sports a talented and perfectly game cast, including Rainn Wilson as a dickish billionaire and Ruby Rose as a slightly less dickish submarine engineer. But once they start getting chummed, it's hard to muster much enthusiasm for the proceedings. This is one of those rare movies where a stupider script and bit more overacting would have come in handy.