Han acknowledges that the Jedi had powers when he dismisses them as "simple tricks and nonsense". It's a big galaxy and there were only so many Jedi to go around, their abilities would have had a legendary quality and he likely never saw one in action personally as a kid. By the time he'd grown up, as he said, he'd been from one end of the galaxy to another and seen a lot of strange things, but however the Jedi did the things that they were supposed to have done, he didn't accept their description of an all-powerful "Force" as the truth behind it, nor the assertion that this "Force" had anything to do with him.
The attitude of the Imperial officer that Vader Force-chokes in ANH also supports the idea that outsiders could be skeptical about the source and extent of the Jedi's powers.
The attitude of the Imperial officer that Vader Force-chokes in ANH also supports the idea that outsiders could be skeptical about the source and extent of the Jedi's powers.