Gold and silver are the marks of a trader who has traded with other traders.
They are the marks of a man who took money with him.
Back before Visa and MaasterCard, when I traveled I took cash and Traveler's Checks (remember them?) with me. Modern traders used the same forms of money, but having money didn't make me a trader.
Sheep and cattle actually make him a farmer, or maybe a rancher. Ranchers sell their livestock for money, and this is where he got his gold and silver.
Traders make their living primarily from performing arbitrage -- moving goods from places where they are cheap and plentiful to other places where they are scarce and expensive. There is no indication that this was Jacob's primary occupation.