'Messengers' in the Bible

Nor did I [even] go up to Jerusalem to those who were apostles before me; but I went to Arabia and stayed awhile, and afterward returned once more to Damascus.

But I did not see any other apostle except James, the [half] brother of the Lord.

Why, then, the law? on account of the transgressions it was added, till the seed might come to which the promise hath been made, having been set in order through messengers in the hand of a mediator --