“By posting content to Patreon you grant us a royalty-free, perpetual, irrevocable, non-exclusive, sublicensable, worldwide license to use, reproduce, distribute, perform, publicly display or prepare derivative works of your content.”
Having such a statement on a website does not in any way remove a copyright holder’s actual copyright, and does not in any way give that website or its owners magical copyright powers over someone’s else’s creation. The creator of any work always retains copyright over anything they create, unless they specifically sign away the copyright for a specific creation.
“Copyrights can be bought, sold, willed to others, or given away. A transfer of the copyright or an exclusive grant or license to use the work is a transaction that must be conveyed in writing.”
In other words, no, Patreon does not own a damn thing its website users put on that website, unless the copyright for a specific creation is specifically signed over, in writing, to Patreon.
Patreon does not have any copyright over anything you have created.
Similarly, you will often see things around the Intertubes such as “Creative Commons”, “GNU Public License”, “Copyleft”, and so on. Do not assume these are in any way actual legal licenses or binding agreements. Most of them are just trendy internet terms and have zero legal weight anywhere (Creative Commons is actually the name of an organisation).
Now if you want to know what copyright, patents, IP, and so on actually are, as opposed to the terms frequently thrown around on the Interwebs…
There’s this thing called the Berne Convention for the Protection of Literary and Artistic Works. You may see websites claim this is “default international copyright”, but that is incorrect. This is a major piece on international law. However, being international law doesn’t actually make it law in any country at all. Basically all these guys and gals from different countries get together and hammer out these agreements, and then various nations agree to ratify some or all parts of it within their own sovereignty as they see fit. This is why, for example, Australia never ratified (and therefore does not have) that section of the Universal Declaration of Human Rights which deals with freedom of speech (Article 19). Anyway, so the Berne Convention is an example of an actual law relating to copyright and IP, and how such things must be ratified by a nation’s government to have any meaning. Different nations have ratified different chunks of the Berne Convention and similar international agreements as they wanted, so some works here, some works there.
Due to the fact that companies want to trade across borders, and get money from as many places as possible, our governments generally agree to a set of rules for these things, so an American company can sell its products in Australia without a local company making a cheap knock-off and destroying that American company’s Australian profits. So however they’re worded or ratified, usually there’s some framework allowing protection of IP across borders. But it’s not always exactly the same, and depends on the local legal system and precedents and such.