In 2018, the film world was introduced to exciting new director Carlos López Estrada and his best-of-the-year movie, “Blindspotting.” Expectations for filmmakers as talented as Estrada can feel insurmountable, but “Summertime,” his sophomore feature film, is a wildly successful storytelling experiment of performance art and spoken word poetry. On the surface it sounds like an arduous undertaking, but somehow it turns out to be the epitome of indie cinema: an ego-less artistic collaboration with zero phoniness. Over the course of a summer day in Los Angeles, the lives of 25 teenagers intersec...