Separate world files for each person's profile using the minecraft launcher on that computer
Solution 1:
You can set the Minecraft Directory in the Profile Editor.
Go to "Edit Profile", and check "Game Directory" for each profile. The game will create new folders for saves, resourcepacks and logs. It will continue to use the appropriate version you selected for the profile (found in the "versions" folder), rather than download the game files again.
You can then move the saves you have to the save folders for the correct profile.