Certain files from the GameSDK require the GameSDK DLL itself. Note that loose files on the disk in the Assets directory will take priority (override) any files with the same asset in any .PAK files. For this reason, it would be better to extract the .PAK files as loose files. Be aware though that certain assets/entities in the GameSDK rely on the GameSDK DLL itself which are ofc not included in the .pak files. Depending on what you want to achieve, it may be better to Import the GamesSDK as project.
e.g: In this case its very likely that the entities.xml as file took priority over the entities.xml file that is within the GameSDK .pak file and this could be the reason that you do not see the Ai/Human under