It's just the ambiguous nature of "improvement" at work here, folks.
Humans are supposedly "advanced" despite having lost (or failing to have gained) such valuable things as high running speed (instead we just have endurance almost unparalleled in nature), protective skin (ours is merely very good at sweating), sharp eyes (ours are merely versatile), or fangs or claws of great reach and potency (we only have our brains).
The Borg Drones have many advantages in the Trek environment. A single individual can hack a starship, a small gaggle can assimilate it, a group can probably outprocess a starship computer. An individual has access to the expertise and skills of tens of thousands of civilizations. That's meaningful
perfection, for the Trek environment; the Drone could be essentially sessile and still outshine the leanest and meanest examples of physical perfection, the most elegant predators, the least conspicuous skulkers, the fastest runners, the least shakeable defenders.