The only reason anyone would have any misconception about what an eclipse was was if they didn't go outside and look at the sky regularly. If you looked you'd see that sometimes the moon shows up during the day and that sometimes it manages to pass close to the path of the sun. An eclipse might come as a surprise to people but you'd have to be pretty ignorant to not understand what it was.

There is a misconception about ancient peoples that they were stupid. The human brain hasn't change much in the last half a million years. There were cavemen that were smarter than Einstein. The thing that has changed over the years is our technology to record, access and share information. People today don't have to figure out how to calculate the length of a triangle's hypotenuse because somebody wrote down and shared the formula. That doesn't mean that person who wrote it down figured out "a squared + b squared =c squared." The concept was actually in use 1000 years before Pythagoras. His recording was just the one that got shared the farthest.