The gun mounting appears too low to fire over crew standing on deck. A crewman near the cannon provides a visual scale for that judgement. The lowered forecastle allows the gun to depress farther.
Notable Point · 1:59:13-1:59:43
A lowered forecastle and the limits of firing over the crew
A crewman's height suggests the gun cannot fire over people on deck, while the lowered forecastle allows greater gun depression.