Humans are complex beings with multiple characteristics of being Carnivores, Herbovores. They have a considerably amazing complex brain compared to other species which can adapt faster than the speed of light on a day to day basis.
Why would someone not be human? Well, being human means you can preform something at life at your own pace/cost/perception. Of course, making errors is something in life that people always make, but that doesn't mean that they aren't human or aren't fulfilling in life.