Having the NPCs tame dinos would present too many issues. There's another way of having them side with dinos though. Simply set humans/dinos in groups together as allies. "Group spawns".

As for bases, have the humans in gangs/factions. Like in the game stalker for example. With the map of lost island there's a number of ruins/buildings so it wouldn't be hard to have humans in factions with decent weapons/armor in those locations. Same concept applies to other maps. Something like the lighthouse could serve as an outpost with bigger places like the walls and ruined buildings serving as a main base. Each faction could have one big base and two smaller outposts. The main bases can have a refinary and smelter as well. Size of factions depends on the map. A map like lost island is pretty big so can have more there.

Slap on a message board that gives quests like "Hunt random dino at random location nearby" and "Retrive artifact and deliver to X NPC/location" (for rewards and reputation) and that gives the player a goal too. Basically like how the stalker game does it in the anomaly mod. Except quests would be from the message board since we can't talk to NPCs in Ark.

As for dinos, just have a setting for X dinos being allied with Y human faction in Z area. They don't have to be "NPC tamed". It's easier to do it that way then to have NPCs tame dinos. Doesn't have to break the immersion either. Can even have the humans/factions attack each other. Sometimes with larger raids. Raids can be small, medium and large. Both in terms of numbers and allied dino size. Example: 3 humans and 2 dilos (small group). Or 12 humans, 2 rexes, 5 arnos (big group). Multiple groups fighting other multiple groups. Now you have a war. A war the player can join. The locations of the warzones would have to be limited to keep the action going. It means more action in those locations though.

Just make sure the NPCs follow clear paths to locations between bases/outposts. Even if this means not attacking the player bases directly it does mean there's a warzone and a no mans land that the player can get involved in/try to take over. As long as the quests are semi RNG (An artifact quest would randonly select which artifact for example) and as long as the factions keep fighting each other consistently then it gives the player something to do that has replay value.

Beyond that it's simply a matter of having the human NPCs equiped with better weapons/armor. Just make them miss the player more often with ranged weapons (like assault rifles). Only a few can have snipers and rocket launchers. The weaker a faction is the worse weapons/armor they have. The more they been building up (they can get stronger over time with locations giving none physical income) the better stuff they spawn with.

Yes !!! Please