Albert Barnes Commentary 1 Corinthians 12:21

"And the eye cannot say to the hand, I have no need of thee: or again the head to the feet, I have no need of you." — 1 Corinthians 12:21 (ASV)

And the eye cannot say to the hand, etc. The hand in its place is as necessary as the eye, and the feet as the head. Indeed, the eye and the head could not perform their appropriate functions, or would be largely useless, without the aid of the hands and feet. Each is useful in its proper place.

So in the church. Those who are most talented, and most richly endowed with gifts, cannot say to those less so, that there is no need of their aid. All are useful in their place. Indeed, those who are most richly endowed could perform their duties very imperfectly without the aid and cooperation of those of more humble attainments.