It has to do with the nervous system. Humans nervous systems developed extremely more precise to have more control over specific muscle fibers. Rendering them over all weaker but tremendously more manipulatable. Animal muscle is so strong because when they recruit muscle it is usually ALL of it. You’ll never win against a chimp in an arm wrestle, but in a thumb war they would not be able to compete. Please correct me if I am wrong I am stupid. But as far as I know thats why apes are so strong and some nervous system affected people like autism and aspbergers are freakishly strong. When precise muscle recruitment is not available, entire groups get activated instead.