One of the main reasons steel is used more widely than iron is because it’s lighter softer stronger than iron

stronger than iron

Explanation: Steel is an alloy of iron mixed with small quantities of carbon.  Iron being a pure metal is soft as the atoms can slip over one another due to the presence of free electrons.

Addition of carbon to iron, makes the iron hard as the carbon hinders the movement of atoms past one another. The tensile strength or resistance to break under applied force for steel gets more as compared to iron.

the largest known star in the universe is uy scuti, a hypergiant with a radius around 1,700 times larger than the

whichever one it is, it's definitely not one that you included on the list you provided.