How many billions of people live in the galaxy? 10,000 is a relatively paltry number. Not to mention that the PT portrays them as mostly hanging out round the temple, rather than exploring.
Also, how old was Han when they went extinct? 15 at the oldest? Even if Han had seen a Jedi use the force at a young age, it’s not hard to believe an older, more cynical version of himself would pass that off as simple tricks and/or nonsense.