The only one who doesn’t seem to know about the Force is Luke, which makes sense seeing as how he lived out in the middle of nowhere and was probably heavily sheltered by Owen and Beru.
Luke is apparently somewhat familiar with the Jedi,though. He doesn’t bat an eye when Ben says he was once a Jedi. It’s only when Ben mentions the Force that Luke expresses a lack of knowledge.
The Rebellion obviously still holds the Jedi in high regard and even uses the phrase “May the Force be with you”. Even Imperials like Motti don’t actually deny the existence of the Force.
Han is a Doubting Thomas, but I don’t see anything unreasonable about that even with the prequels in mind. As others have said, it’s a big galaxy and it’s unlikely he ever saw a Jedi in action.