Yes. That is the value of single tickets on carriers with baggage interline agreements and connections conforming to the time limits on baggage (12 hours for AA). This connection is particularly easy at JFK because you clear US CBP at YUL and are thus a domestic arrival at JFK and your bags head straight to their onward carrier.

If you have the AA app loaded, you will be able to see your bag offloaded at JFK and then handed off to BA and you may then ask any BA agent to confirm that BA has the bag.