One of the highest grossing and critically acclaimed independent US films of 2018,”Eighth Grade,” the extraordinarily assured feature film debut by writer-director and standup comedian Bo Burnham is touchingly real, so embarrassingly true to life, you might swear it was improvised, or found footage. But it’s not. This is Elsie Fisher, a 13-year-old actress herself, amazingly in touch with what it’s like to be in the stage of life she’s actually in. Kayla airbrushes out her acne, and swoops on heavy eyeliner. When you see what her life is actually like the Kayla’s Korner videos take on an almost tragic significance. But it’s strangely hopeful too. This is a young girl trying to understand what she is going through, and she does so by positioning herself as an expert and a helper to others. Surely one of the year’s most notable writing and directing debuts, Bo Burnham’s “Eighth Grade” gets as close to the heart, mind and soul of a young person as a movie can. Indeed, the biggest conflict in “Eighth Grade,” the scariest antagonist, is us, being too hard on ourselves. The miracle of Burnham’s film is that it understands, and forgives.