From what I understand, early colonists brought back coco leaves from Peru and cannabis, so why was it that tobacco became the most common leaf to be smoked?
Cannabis isn't from the Americas, it originated in Asia.
It's worth mentioning that instances of smoking coca, both in the present and in historical/archaeological records, are few and far between. I've done it enough myself to profess to the huge popularity of chewing it, but that's all you can ever expect to see.