Is There Such a Thing as ADHD?

If we accept that there's no such thing as a typical brain, it begs the question, why did we evolve to have such diverse brain types? It does feel to me to be highly logical that in our ancestral environment, it would be an advantage to a given tribe to have some people who were, let's say, highly anxious and woke up easily. And so my almost perfect wife describes yourself this way as being, she's, you know, can be relatively high on the anxiety threshold. She thinks of herself as the watchtower woman. There might be some folks who are obsessive compulsive and love to weave baskets. I'm being a little reckless here. But what do you think