Yeah, a lot of copyright law in the US is extremely forgiving towards creators making mistakes. For example, you can only file for damages after you register the copyright, but you can register after the damages. So like if I made a book, someone stole it and starting selling copies, I could register for a copyright afterwards. Which honestly is for the best. Everything you make inherently has copyright. This comment, once I click send, will be copyrighted. It would just senselessly create extra work for the government and small creators if everything needed to be registered to get the protections.

Edit: As an example of this, this is why many websites in their terms of use have something like "you give us the right to display your work" because, in some sense, they don't have the right to do that unless you give them the right. Because you have a copyright on it. Displaying work over the web is a form of distribution.