It is not possible that there were humans in the meteorite that killed all dinosaurs. Taking into consideration that the dinosaurs are very adverse animals yet they could not survive the heat, humans would be badly placed.
No. If the didnt die due to heat from entry to the atmosphere, the impact with the earths surface would have vaporized them just it did the supposed meteorite. However if you wanted to write a sci-fi story along that line it might be interesting.