Zayd belonged to the Ansar, the Medinan supporters, of the clan of Najjar, and he was a boy when Muhammad arrived in the city. The tradition says he was too young to fight at Badr and was turned back, and that he was set to learn the script used by the Jews of Medina so that correspondence could be handled without an intermediary, which he did in a matter of weeks. He served the caliphs afterwards as a secretary and was left in charge of Medina when Umar travelled.
He is also remembered as the leading authority of his generation on the division of estates, a technical subject with a great deal of arithmetic in it, and later works on inheritance cite him constantly. He was close to Uthman, and during the civil wars that followed he kept out of the fighting.
All of this comes from inside a single tradition. The biographical literature that preserves it was compiled by scholars for whom the authority of the Quranic text mattered enormously, and one named collector working under two caliphs is a cleaner account of transmission than a diffuse one would be. That is not an argument that the account is false. It is a reason to notice that no independent source exists to test it against, and to say so rather than present the story as though it were corroborated.