Your are right, the OP did not mention nonstop flights. As I had been monitoring prices from the same airports I assumed that airfares the OP mentioned were for nonstop flights. They are consistent with nonstop fares that I and others have found.

I often get sucked into to the low fares that pop-up on Matrix. Until I realize that the 1 stop flight is actually 8+ hour trip. For me, it's hard to justify the savings when I could be in Jamaica in less than half the time without the hassle of changing planes. Looks like all those cheap flights are JetBlue flights with long (4+ hour) layovers. The same is true for Southwest (which doesn't come up on Matrix or Google flights).