It's easy for us to understand that The Doctor is a sapient being.
After all, he acts like one! He's got a slew of odd personality quirks, balances irritating behavior with kindness and sympathy, behaves in a similarly slightly erratic manner as most of us flesh and blood creatures, and responds to difficulties with every appearance of genuine emotion. It's extremely easy for human audiences to look at the early seasons Voyager crew as bigoted for their slow acceptance of him as a "real" member of the crew, and react very harshly to later challenges to his personhood from people outside of the crew. It's not uncommon to see that behavior referenced as proof that 24th century people are no more "enlightened" than the obviously flawed people of today. And maybe they aren't; that's not my topic for today.
But the element I think that argument is missing is something these 24th century people have been exposed to all their lives, and we in 2024 have only begun to encounter: soulless, unconscious entities capable of impressive imitations of a real person.
24th century holograms appear as perfect copies of physical humans, with perfectly recognizable voices, normal human mannerisms, and convincingly human speech that responds naturally and automatically to nearly any expected or unexpected input. Any of us unknowingly tossed onto a 24th century holodeck would be totally convinced that these people projected around us and interacting with us are as real as anybody we meet today: nothing they do will clue us in to the fact that we're interacting with philosophical zombies.
Most of us first encountered something like this when ChatGPT and it's ilk suddenly got really good and easily accessible just a couple years ago. Suddenly a computer could create text that read like a human had written it, responding to context and occasionally interjecting very human behaviors (like making up answers to stuff it didn't know, and attempting to gaslight anyone who called it out for being wrong). A shocking number of modern people seem to genuinely believe that these bots show real consciousness (even some who really ought to know better). And it's not hard to understand why, when these bots can spoof every text-based indication of humanity that most of us look for.
People of the 24th century have spent their entire lives interacting with bots that smash the Turing Test even more thoroughly, and on every level imaginable. They can walk onto a holodeck and spin up a person from scratch who looks, smells, feels, and sounds completely real, who talks coherently and shows perfectly ordinary physical mannerisms. And they also know, with ironclad certainty, that these creations are no more human and no more alive than a tricorder or a hyperspanner. Just about all they have to definitively prove if someone is real or not lies in if they can exist outside the holodeck.
Enter The Doctor. He's very definitively a hologram. When first activated he's no more real than any other holographic creation, and only slowly grows in unanticipated ways which slowly convince his crew that he's become something more than that. This process is slow, but it's actually a bit of a surprise that it happens at all. Excepting Kes and Neelix, everyone on Voyager is quite accustomed to holographically generated people who act human but are purely a facade. That this very reasonable prejudice could be overcome at all should be seen as a triumph of empathy. It's not at all surprising that the people back home on Earth aren't buying it, and can't even be persuaded beyond a bare minimum threshold of plausible uncertainty.
I theorize that people who are growing up right now in an environment of very convincing AI chatbots will find it easier than we did to recognize holographic beings in Star Trek shows as sophisticated extensions of those internet bots, and will mirror the slow acceptance by Voyager's crew that The Doctor is something more than that.
So what does that mean for us? What do we do as more of our instinctive indicators of another person's humanity are effortlessly aped by machines? This is a difficulty which Star Trek shows had only begun to grapple with, but it's fertile ground for future episodes and undeniably a relevant question for our day.
Nomadic people don't just wander around aimlessly, and there are big differences in how desirable different territory is for nomadic hunter-gatherer humans. The principle is the same as with nomadic pastoralists: your group has a territory which can sustain them when hunted on/gathered from/grazed/etc over the course of the year, and your group will wander within that space in a deliberate pattern. If some other group decides to "just move on to" your group's territory, hunting the animals and foraging the plants that your group knows they are going to need to survive the year, that's an existential threat to you. And you can't "just move on" yourself without wandering into the territory of yet more groups whose territory borders yours, and who will react violently to your presence for the same reasons.
Given the choice between fleeing to who knows where and fighting who knows who for the privilege of moving, or staying right where you are and fighting for the land you know your group can survive on, you stay and fight.
Humans spread out across the earth as the losers of these conflicts (those who survived, anyway) fled until they stumbled on new-to-humans territory, often displacing or eradicating groups of more "primitive" hominids they found there. This process continues until just about everywhere which humans can reach and which can support human life has humans in it. But expanding populations, the occasional natural disaster, and normal human frustration that their territory sucks while their neighbors have it great (which was often true; again, not all land is the same to a nomadic hunter/gatherer) meant that these conflicts were constantly reignited.