the most important parts of the world are the "level.dat" file and the "db" folder, which control world metadata (such as name and default gamemode) and chunk data respectively, but some worlds also come with other things, such as a "resource_packs" folder and a "world_resource_packs.json" file.
these (along with any other folders and files associated with the world) should all go into a folder specifically for the world which is itself inside the "minecraftWorlds" folder. do not place the individual pieces of a world into the "minecraftWorlds" folder by themselves. the name of the world folder doesn't matter (though older versions of the game have trouble editing worlds with a space in the folder name), so, if the world was zipped correctly, you should just be able to ctrl-x ctrl-v the folder you initially extracted the zip file into directly into "minecraftWorlds".
alternatively, you may be able to just turn the zip file into an mcworld file and run that.
if the world you're trying to import is from education edition, you may have to replace the "level.dat" file.
hope this helps!
