What did Magellan seek to prove when he set out from Spain in 1516?

Ferdinand Magellan set out from Spain in 1519, not 1516, to prove that a westward route to the Spice Islands (the Moluccas) was possible and would be shorter than the eastward route around Africa. He aimed to establish a direct trade route to the lucrative spice markets of Asia. Additionally, Magellan sought to demonstrate that the Earth was round by circumnavigating it, thus providing tangible evidence of his theories about global geography. His expedition ultimately succeeded in proving both the feasibility of the westward route and the vastness of the Earth.