“I just had a realization around my thoughts on ownership. For something to be "privately owned" is based on the belief that all humans are separate from each other and the rest of life on Earth”

Why would it have to be that humans are separate? I mean in a way humans are separate from other things, that is why the word "humans" is useful. The reason I think it makes sense to have certain agreements between people and not between people and other animals/plants/elements is because humans have a higher capacity for abstract thinking and can communicate with each other. Also, humans are the most dangerous form of life on earth at the moment, we have a huge capacity for destruction and evil. And even if a virus or bacteria became a bigger threat to human survival we wouldn't be able to reason with it. So it's important that people can agree to get along, and most disagreements are about ownership. So how do you handle disputes without land ownership? Let's say everyone agreed that no one can own land, would that not lead to avoidable conflicts?

"The idea of land ownership is definitely based on the threat of violence."

Well, I don’t see how. It's true that the way to protect one property can involve violence and probably will include the threat of it, just like self-defense. Is the idea of owning yourself based on the threat of violence? The question is who is the legitimate owner? We agree that it is the robber who initiates the violence if he tries to steal your wallet, right? But if you base your argument on the statement that no one can own a wallet then if you accept this premise the aggressor is the one that uses violence to defend “his” wallet.

"The idea of land ownership is definitely based on the threat of violence. If I wander onto a piece of land, the only way to claim ownership of it is to put up a sign threatening violence if I enter there, which would by definition make the "owner" the aggressor in any conflicts (assuming the "trespasser" didn't come on to do harm to the "owner" or others."

Well, you could just put a fence around the land without a sign. Let's say you do this and someone walks up to the fence. Wouldn't it be reasonable for the person to ask themselves "gee, I wonder why someone put a fence here?" Maybe they did it because they are growing food inside the fence or they have a dog or something. You could go around the fence or ask the owner if you could cross.

A reasonable person wouldn't kill the "trespasser" in cold blood as soon as he jumped the fence, especially not without giving a warning. A more likely scenario, if the fence is jumped, is that the owner asks what the trespasser is doing, if they need help with something or if they are looking for someone.

“That depends. If, in this free market, I "own" a piece of land, and that land has millions of money-units worth of some kind of mineral underneath it, then my market-incentive would be to rip the place up and pull that valuable item out to sell it.”

Is there something inherently wrong with mining? I can understand the moral objection if you own a house and someone rips out the ground under it causing your house to fall into a sinkhole. But if it’s your own house you have the right to destroy it if you want. Besides value is subjective so if you value not ripping the place up more than you value the millions of money-units worth of mineral you would choose to leave it in the ground.