Sin was everywhere but God still loved the humans. He wanted to bless the world but for this to work, he needed a guy called Abraham. God told him that he would have lot of descendants who would live in promise land and the world would be blessed.
Abraham didhave many descendants but they were enslaved in Egypt. The people didn't like this one bit so they cried out to God. God then gave them Moses who led them away from Egypt.
Finally, Abraham's descendants and Moses arrived at the land and they were over the moon with joy and started their civilization.
Unfortunately, they immediately turned on God and started worshipping false gods and completely ignored him and his ways. Eventually, the people asked God for a king.
God gave them David and said that his family would always rule over the people. The type of king was called Christ or The Messiah. Even the kings after David rejected God so he sent prophets to warn them to turn back to him otherwise they would be exiled from the land.
The people still ignored God and enemies wiped them out. In the end, some of the people were allowed to return to the land but it was never the same as before. To this day, the people are still waiting for God's promise to be fulfilled.