"If we're having a conversation to have a conversation, what's the point?"

You're actually halfway there with the question. Indeed, the point is not conversation, or at least not the literal contents of the conversation.

When I was younger, I had a hard time understanding this stuff too. I'm not 100% sure why (I'm not convinced I'm even slightly on the spectrum, but it's not out of the question entirely; it's also just possible that I was simply too different as a kid from the other kids), but one of the steps to resolving it is just to realize that yes, there is logic to almost all of what is going on, and it isn't actually that complicated of a logic either. The biggest impediment to not being able to understand these interactions is the belief that you can't understand them, or that there's some sort of virtue in not understanding them. The second-biggest impediment is the belief that these things are essentially irrational, in the older sense of "essential" as meaning something like "inseparable from the whole"; there is actually a level on which this is all shockingly rational behavior. Once you get over those ideas, and accept that the surface levels and what's actually going on in the relationship between two people is not the same thing, it doesn't really take long to figure out what's going on.

(There's... a few other ideas you'll find you may want to discard. For instance, while politically incorrect today, there are reasons to be initially distrustful of people not in "your group". If you can't believe that's true today, it was certainly true in evolutionary terms. So there are instinctual protocols for determining whether someone is "in" or "out", and there are reasons for them, and there are reasons why they involve difficult-to-forge signals like simply knowing some in-knowledge from a culture, or burning time on seemingly-inconsequential conversations. And these things operate at instinct level; it doesn't matter if you think they are wrong, out of date, or politically incorrect; they do what they do anyhow. Start putting a few of these things together and it all starts making much more sense. There's reasons why these things exist and persist.)

Unfortunately, I don't really think I got what you were intending to say with this message.

You basically said there 'is' a reason for inconsequential conversation, but then only proceeded to hint at it's existence outside the last paragraph, and that was described as a different idea I might want to discard.

As such I can only hope that I'll eventually figure it out as I get older. So far the only thing I'm finding out as I get older is that humans are indeed irrational, and that often you just have to deal with that.

a lot of time it is to signal interest and create so called social lubricant. It is not about the content of the conversation, but more about having a conversation with someone from the group.