They certainly didn't treat other humans anything different. In those days "us" meant the tribe or family group. Everyone else was "them", sometimes an ally, sometimes a foe, depending on the situation, resource scarcity and the power of both sides. And those were the violent times, so when there was no enough food for everyone, competition (whether it's human, neanderthal or animal) had to be either scared away or destroyed. That's how all creatures in nature function, it's a matter of survival, there's nothing unethical about that.
It's important not to underestimate the intellectual life of ancient cultures. They were humans, with language, and probably had music, stories, traditions, religion, conflict, politics, and more. Methods of oral traditions have been identified that are essentially equivalent to modern memory athlete techniques, hundreds of thousands of factoids could be transferred with very little "bitrot" over generations. There are traditions in Australian aboriginal cultures that go back 40,000 years, and very sophisticated memory techniques that perpetuated their culture.
The relations between tribes near each other would have been as nuanced and varied and sophisticated and weird as any collectives of humans in relation to each other in modern life. "Those asshats downriver are rude, but they trade fair"
Modern life has given us profound advantages over previous generations, but we are basically the exact same kind of creature as plains walking humans from 300k years ago.
The notion of primitive simple hunter gatherer tribes doesn't account for the innate complexity of individuals. Their experience going through life would be the same as ours, we just have better (on most measures) tools and knowledge.
We are a lot less violent on average, though. Hunter-gatherer societies tend to war a lot. We don't see it as high-intensity conflict because of the low casualty numbers and lack of pitched battles. But when you look at it as percentage of the overall population, it turns out to be worse than our worst conflicts.
(To be clear, not all hunter-gatherer societies are like that. Some are more peaceful than others, and there are extremes like the Moriori. But the average is what it is.)
