Hanbin,
the confusion is caused by the fact, that "recents" is not a folder like the other folders in the Favorites in the sidebar. All other folders in the sidebar are showing you a place, where you are seeing the files and documents saved there. You are seeing there the folder where the items are stored.
But "Recents" is a different view of documents stored elsewhere, a predefined smart folder, like a saved search. On previous system versions we had a similar smart folder, called "All Photos". It has been a saved search of all photos stored on the Mac. The"All Photos" smart folder caused many users to delete all photos, because they could not tell, that they are viewing a smart folder and not a regular folder with additional photos.
You can see, that Recents is a smart folder, by ctrl-clicking it in the sidebar. The contextual menu does not have the options "Show enclosing folder" and "Get Info", because there is no enclosing folder and it is no folder with an Info. "Recents" is no place.

But the Downloads folder is a proper folder and has an enclosing folder and has an Info:
