There is, but Windows makes you work to get to it. It's c:\Users\[your name]. It's also hard to get to, since Windows doesn't make it a shortcut by default.
This is called the User Profile folder and its directory path is stored in the system variable %UserProfile%. Windows does provide shortcuts in the Windows Explorer file chooser for key subfolders, such as Documents (My Documents in older versions of Windows), Downloads, Desktop, Music, Videos, Pictures, etc.
The out-of-the-box default for major browsers like Chrome and Firefox is to save downloaded files in the Downloads folder, which has the path %UserProfile%\Downloads. However, it is generally possible to set a different target path in settings, to require the browser to prompt the user to pick a folder, or to save in the last used folder (and, if it no longer exists, to prompt the user for a new folder). Firefox subdivides folder assignments by server, which means that if I save an article from the online Wichita
Eagle, it will usually go into an "articles" folder, while if I save something from the TxDOT FTP server, it will go to a subfolder in my "TxDOT Plans" folder.
It has been literally years since I last had something save to the Desktop. I can't imagine a scenario where a file would save there unless it was hard-coded to do so because the Desktop is guaranteed always to exist. This behavior used to be quite common for program installers, but now they usually save in Downloads unless a different target folder has been configured.