The stakes feel immensely low in “ The Marvels,” and it’s not because this is a movie that spends a fair amount of time following cats or has an out-of-nowhere musical number. It’s possibly that somewhere along way, Marvel movies just stopped feeling like events. And this galactic trifle from director Nia DaCosta does not seem to be the one to make them feel like a must again for anyone who has not kept up with all their Disney+ series and who has forgotten what phase the MCU is in and why it matters.