Liftoff does the trick for me

Syndicate and Wing Commander Privateer

Most difficult imho would be to explain why we haven’t advanced any further. If the person is 50 in 1950 he started with horse carriages and saw development to intercontinental bombers, rockets etc. The landing on moon would astonish him, advances in medical sciences and computing too but he probably would ask: “And what are you using that neat little gadgets for?”