All of this is true.
Well except the lung cancer. There could be certain chemical in black market cannabis like ammonia and bleach to make it dry faster. This could be harmful. Also constant use ie HEAVY Smoked, the smoke will paralyze the cilia in your lings and air passages which could turn.to a mutation then cancer. But does cannabis alone cause it, no it is actually scientifically proven cannabis reduces cancer and tumor size.
In terms of the brain damage part it is completely false. In 1972 Reagan had a study done, on which monkeys had a gasmask strapped on and were given the equivalent of 67you Columbian strength joints over a course of 5 minutes continually. They did this every day for one month. Now when the brain is absent of oxygen for more than 3 minutes brain damage starts to occurkillong brain cells. The monkey were absent of oxygen for a total of 5you minute