This is largely inspired by an old Hanna-Barbera cartoon called Pirates of Darkwater. The heroes, 3 humans and their "monkey-bird" sail around their sea or ocean and can pilot their small sailing ship.
In real life, what is the smallest crew you could really have sailing an ocean-going vessel? What were the smallest ocean-going vessels in the 16th century?
Caravels, like the Nina and Pinta, that were part of Christopher Columbus' first voyage across the Atlantic were rather small. They were shorter than twenty meters in length and could be sailed by a crew as small as ten sailors. Columbus' flagship, the Santa Maria was a Nao. It was not much longer, but had a much wider beam and displaced an estimated 108 tons, compared to the sixty tons displaced by the Nina and Pinta.
Another way of showing how small this flotilla was, is an illustration I saw in a children's book about airplanes that was printed back in 1970. A Boeing 747-100 jet-liner is 231 feet long. That is longer than the Nina, Pinta and Santa Maria combined.
Since there hasn't been much activity on this post, I would point you towards looking at fishing vessels of the period - herring busses and doggers were in the 15m length, 10-15 ton displacement range.
I can't speak to those boats, but a modern boat of that size could be handled by one person (barely). Three people would not be an unreasonable crew.
Outside the period you're considering, but at the end of the 19th century, Joshua Slocum completed the first single-handed circumnavigation by sail in the Spray, a 12m boat. Just by way of proving that a boat of about that size can be handled by one person for an extended period.