The ability to speak isn’t solely a product of intelligence. The transition from the pharynx (throat) to the oral cavity (mouth), is 90 degrees, which provides unique acoustic properties when combined with the oral cavity being roughly equal in length to the pharynx, as well as the rounded tongue. Chimpanzees have flat tongues, extra long oral cavities, and a far greater angle at the transition point from throat to mouth. Even super intelligent Chimps wouldn’t be able to speak like humans.