You're right that Palestine has sought recognition in international institutions and is recognized as the state of Palestine before the ICC.
Of course, I think what's important to highlight there is an attempt of the Palestinian people and some leaders in Palestine to seek law and not war. International law is profoundly imperfect, but it is an avenue and can sometimes be an off-ramp offering people hope aside from seeking further violence. I think that Canada's recognizing Palestine won't in and of itself change the landscape, but it can lead to important diplomatic and legal consequences for Canada as well.