To understand the concept of the universal unconscious, you first need to ask yourself a question. "Why aren't we all sociopaths?"
The root of the question is why we care about each other at all on this planet. It would make more sense for us to carefully choose allies and people we can manipulate easily, and then take everything we can and retreat to our fortress. Something other than fear of incarceration or execution keeps us from killing each other. Ask anyone who has shot someone for the first time and they'll tell you it is really hard when it comes to that moment. Why should it be? This person is a threat. Killing them is a solution that eliminates the threat.
Many people do come close to thinking and acting that way. They are driven by selfish needs that have no concern for the welfare of others, whether it is in search of wealth, power, or something else, they are in search of something they can never attain. The accumulation of wealth just to be able to say you have it so that others will look up to you in wonder is very much like being an addict. It is most easily compared to a gambling addiction, which is something I am myself in recovery from (19 years and counting), where you aren't thinking, "That big win gave me enough money to pay all my bills this month." You are thinking, "Must win more! Must accumulate more money!" It doesn't matter if you already have enough money to afford all the things you ever wanted and to live in luxury for the rest of your life. One has to have more.
If we liken this type of hoarding of wealth and resources to an addiction, the rest of the picture looks clearer. Those folks have, through history, been those celebrated and seen as examples of success for centuries. If you wipe that off the chalk board and consider them the anomalies in the system, those who have fallen prey to their own weaknesses, you can almost see that there is something that is binding us all together. Empathy is like a translator. Why does seeing an old woman walking in great pain and difficulty cause us to want to help her, or even to feel badly for her having to suffer like that? Why do we give a shit? Is it because we are "good people"? Is that all there is to a fire?
Something binds us together on a level we cannot see or even comprehend. Every other explanation of why any of us care about anyone else, other than what we can get from them, is incomplete. This is the origin of gods and of mythology. Why aren't we all killing each other so we can have each other's stuff? It isn't fear of arrest or prison. When someone offends you do you think, "I would slaughter him like a lamb right now but I don't want to do prison time," or do you think, "Fucking asshole, get away from me you piece of shit." Yeah, you get pissed off, but are you really wishing there were no consequences for killing this person who offended you? Is it fear of eternal damnation? Atheists have the same problem. It is more than fear of punishment or being taught that killing people is wrong.
As a suicide survivor who once had a chance to kill someone I will tell you that the barrier we have, the restraining bolt inside of us, that makes it really hard to kill yourself is the same barrier that makes it really hard to kill someone else. Killing someone else and killing yourself produce the same internal response. You need the nuclear codes to authorize it. Why does it feel the same? We're all connected.
The real convervence point of all mythologies is here, trying to figure out why we give a shit about each other. It doesn't make any damn sense.
They all grow out of the same soil. That soil consists of two questions. Why do we exist? Why do we care about each other?
Everyone knows the first question, the so-called ultimate question. They don't think as much about the second question. Most take it for granted. That which binds us together is, for me, the much deeper question. There are creator gods who explain us coming into existence in what is the orginal deux ex machina. Those who accept that answer usually tie it into the second question. Often it is explained that the creator god or associates demands it of us. The less common answer is that we are created that way.
Gods are personifications of concepts and ideas, and of translations of that which cannot be known or understood. What cannot be explained or answered must have a reason. The question is hard. Easy answers make the hard go away.
That which connects us to each other in different ways also gives us an internal command that is difficult to override.
Spiritus Mundi is an apt description of this which connects us all. There is no reason to work for the benefit of all mankind, except there is. We have no other reason for existing.