“I might be young, but I ain’t stupid,” sings Meghan Trainor on the brassy “Lips Are Movin.” We knew that already: the sharp-witted lyrics and bubbly hook of “All About That Bass” made the singer one of pop’s most exciting newcomers of 2014. Trainor’s debut album, Title, is a parade of lovable, bobble-headed pop. Tunes with a future-‘50s feel (like the smart-alecky “Dear Future Husband” and the John Legend duet “Like I’m Gonna Lose You”) shimmer alongside playful fusions of R&B, hip-hop, and dancehall (“Mr. Almost,” “Walkashame”). The hooks are undeniable and almost uniformly uptempo, but when Trainor slows down to croon along with a string section on “What If I,” the firebrand phenom channels the heartbreak of vintage Etta James.