Bromelain does indeed come from pineapples, however it is made from the stem, not the fruit. Bromelain is excellent for wound healing and is anti inflammatory.
Canned pineapples do not have the active enzymes that fresh pineapples have.
For those of us who were around in the '50s & 60's when desert was often Jello with pineapple chunks, it was well known that you had to use canned pineapple or your Jello would not setup. The enzymes in fresh pinapple would go to work and keep the mixture liquid.