В чем разница между I can't get through because so many people are in my way. и I can't get by because so many people are in my way. ?Пожалуйста, приведите примеры.

in this case they mean pretty much the same thing but it could depend on what happening too. If you're walking through the middle of the crowd, through fits more, and getting by can describe moving around a group along some kind of wall better, but its not uncommon for both to be used interchangeably.

In English a lot of verbs can be taken a little less literally since they can be used in a lot of ways depending on the phrasing but it always depends on how its being used as well so if you're ever not sure there's a difference always check.

i hope this makes sense