Kennedy ran a personal best 9.85 seconds to beat Patrick Johnson's mark of 9.93 set in 2003 to claim a silver medal behind Cameroon's Emmanuel Eseme (9.83) in the Games' fastest 100m final on Tuesday.
Lewis improved on her own 100m national record in the semi-finals and raised the bar again in the final, taking bronze in 10.99.
"Far out ... we got a medal in every event we competed in," 22-year-old Kennedy told Australian media.
"Aussie track is clearly in, I think, the best spot it's ever been and our team is so strong.
"We're in a real golden age with a lot of youngsters and a lot of good veteran talent as well."
Kennedy became the second Australian to legally break the 10-second barrier in the 100m when he ran 9.98 seconds at a meet in Kenya last year.