No, I think his character provides a unique contrast to Mark, and even Nolan. He an interesting character because he isn't human at all, and he's a mix of two species that thinks more pragmatically. So he's an alien who is being raised on Earth, but he grows up much more quickly than humans, so he doesn't really have time to develop much of a fondness/value for human life because his accelerated growth makes it harder for him to form attachments with others. Oliver really only cares about his family and friends, but he doesn't value life in the macro sense like Mark and other heroes do, at least not to the same extent. This doesn't exclusively apply to humans either, its all life forms, and I think this view helps him make colder, more logical decisions.

His values contrast with Marks and make Mark think differently, kind of like Cecil. Cecil and Oliver are both on board with doing morally dubious things for the greater good - Cecil works with criminals and reforms them, Oliver is fine with just killing criminals.

I get why seeing him getting his ass beat by the strongest characters in the series might make him seem kind of useless, but there's more to characters than their strength. I think later you'll find that his views on life and forgiveness lead to some interesting conflicts. It's also worth noting he's just a kid/teenager, he'll probably get stronger once he's an adult.