The antonyms for the phrase "more humpbacked" are straight-backed, erect, and tall. These terms describe a person who stands upright, with their shoulders and spine aligned in a straight line, without any curvature or hunch. Someone who is straight-backed appears confident, poised, and self-assured, while someone who is humpbacked may seem timid, shy, or insecure. Being straight-backed also promotes better posture, reduces the risk of back pain, and improves breathing and digestion. It's important to maintain good posture throughout the day, whether sitting, standing, or walking, to stay healthy, happy, and confident.