The correct answer to this open question is the following.
The important contributions that Washington made that helped the Americans win the war and establish a lasting republic were the following.
General George Washington was considered to be a good leader. Yes, he was a person who could inspire and rally his troops under the most difficult conditions. And he took these traits to the presidency of the United States, and that is how he became the successful first President of the United States for two periods and had the respect of Federalists and Antifederalists that were part of his cabinet.
Let's have in mind that as the General of the Continental Army during the Revolutionary War, Washington faced many problems. Among them,
the lack of money, problems of transportation, inexperienced army, and poor organization.
General George Washington knew the Continental Army soldiers were poorly trained and had minimum combat experience. That is why Washington called the help of Prussian military Official Baron Von Steuben during the winter of 1778 in Valley Forge. This Prussian military really helped to train the American troops.
Actions like these helped him to be considered a great leader.