By seeking out novelty, someone could be a more effective forager or better able to spot predators/prey hiding. ADHD often comes with a high attention to detail, so there's lots of advantages that could come with that (e.g. that twig wasn't broken before, something has passed through here).
Also, having different sleeping patterns can mean that the people with ADHD are likely better equipped to keep a fire burning overnight and possibly be alert for predators.
I think there is a conflation between attention and attention to details. I understand attention control can vary depending on the engagement value of a task. I have experienced the condition my entire life, I am well aware.
I am not aware of any data that supports being interested in a task lessens the likelihood of making mistakes. If you have any data, I will gladly read it.
Also, having different sleeping patterns can mean that the people with ADHD are likely better equipped to keep a fire burning overnight and possibly be alert for predators.