[rakoo]

> I think they must have worked to some benefit to bring us here.

No, the other consequence of evolution is that whatever we are today is not enough to kill us. Some of the things in our bodies and behavior are just useless, but not bad enough that they endanger our life and cut the genetic deviation responsible for it, so it just keeps on being there.

There's no good reason we still have 5 fingers on feet, but they're also not bad enough that having them all would endanger us as as species, so they just stay there.