This can likely be explained by a google post by Rob Pike about the origin of hidden files.
In the early days of Unix there was no concept of hidden files but the files
.. existed to represent the current directory and parent directory. It became annoying to list these files every time
ls was used so a simple change was made to the
ls program to hide any file beginning with a
.. This change, had the unplanned effect of allowing for "hidden files".
As Rob Pike explains:
As a consequence, more lazy programmers started dropping files into everyone's home directory. I don't have all that much stuff installed on the machine I'm using to type this, but my home directory has about a hundred dot files and I don't even know what most of them are or whether they're still needed. Every file name evaluation that goes through my home directory is slowed down by this accumulated sludge.
So to answer your question those hidden files you didn't create are likely some sort of config files from applications you have installed.