What contributions did george washington make in the creation of our government?
why were these contributions so significant?

Simply put, George Washington's work while he was the president was the main reason why plenty of precedents are now available. He also established the government system, which of course, helped establish what we have today in the United States of America. He also ensured that the republic could be saved by making sure to follow justice, nonpartisanship, and restraint among others. The presidential office system was also made by George Washington. 

They made a checks and balance system to equal power within the branches. the "check" meant that one branch would watch one branch and "balance" them if they were too powerful. if you want more info on this, i would just google checks and balance system.