Nah not that high. A lot of it is cockney as well. Basically a mixture of cockney, jamaican and black american. Nowadays you're getting more African influence as well.
To address your last statement, I know the terms dont come from the UK because there has never been a UK influence, or even UK people, in the small black urban communities from which this slang sprang and is mainly used. UK people in Canada are virtually always upper heel white people.
Now, you probably only hung out with well heeled people and/or non blacks during your visit (contrary to popular Drakenian belief, most people in Toronto are non black). Toronto has more than 5 million people and terms like bare, man dem, seen, etc ae mainly used and associated with t urban housing blacks. The normal whites, Asians, Indians, etc who make up the majority of Toronto don't use the terms. You have to look for dark and brown nikkas going to Central Tech, random people going to or who went public schools, even Somalis etc. Your saying terms like man Dem, bare, seen, etc isn't Carribean based on whom you encounter as a tourist is like saying New Yorkers don't use B every couple sentences because you only encountered rich New Yorkers who moved to Manhattan last year from Ohio.
Indeed, there has always been an American influence in Canada but terms like bare, Man Dem, etc come from Carribean and/or Jamaicans. We can eliminate the notion the British came up with the terms because black urban communities (which are dwindling now) in Canada have no British people (whether white or blavk). Historically only immigrants non whites from poor countries and some poor Canadian whites (whose base culture is similar to Upstate New York) live in Toronto urban communities. There are no cockney British people from which to originate any recent cultural developments and explain this term use.