Everybody can be helmsman except luffy. But jinbe already shows some certain level of helmsmanship

He knows sea and he can do something about it.
Jinbe is positioned in helms actually connected to his dream agenda. The helm is on the front deck. So he wants to shows that fishmen and human can get along.
jinbe is a great addition. He is expert in helmsman and swimming and great advisor regarding alliance
[automerge]1623062662[/automerge]
if you really think about it every SHs dreams really fit to their roles or what they usually do
For example
Zoro dream is WSS. It's demand him to become strong that's why he always training. His role as combatant fits to what he always do in daily basis
Usopp dream is to become knight of the sea. It's so abstract but he is trying to become stronger by his own way with his marksman skill, by come up with new tools or something. Do you all know usopp also has a pop green garden and a factory in the ship?