After all those hit-and-miss “Alien” sequels, it’s comforting to see “Alien: Romulus,” a sturdy entry in the canon that reminds us of a day when summer films were reliable tent poles.

For years, Alien films have been getting made ever since the 1979 original captivated audiences. For a little while, the Alien films were a sort of sacred and special thing, especially in the late ...