In Addition to the answer here which is all correct.
Regarding your first question, about if the Canaanites did anything evil to the Jews prior. No they did not.
Regarding your second question about it simply being the will of Gd. Yes it was the will of Gd, No, it was not "simple".
In the book of Bereshit (Genesis) Abraham tells his children not to marry the people of Cannan. Even though he left his home, his father, and his country because of their idolatry , (as seen in Lavan's House); Abraham still preferred that his children and grandchildren marry someone from his old home, rather than marry a Canaanite.
It appears based on various verses of the Torah, that the Cannanites were involved in morally repugnant practices that so infused the land and culture, that the strictest rules were placed around our possibly being influenced by them.
Some of the repugnant behavior that they engaged in included being inhospitable to guests, lacking kindness, child sacrifices, body mutilation, and extreme superstition beyond the norm for a society.
This was a societal problem, not just some individuals, as the Tanach shows us, some individuals went against the trend of the society.
Throughout Tanach, we see that the Mercy that Israel had against the inhabitants of Cannan, became the cause of many problems for the Jewish people because they followed in the ways of the Cannanites, even after the Beit Hamikdash was destroyed, close to 1,000 years later.