Rationale behind Date created, Date modified` & `Date` on Windows 10

I am trying to understand the rationale behind Date created, Date modified & Date on Windows 10 File Explorer.

Yesterday, 30th June 2020 I downloaded a Youtube video and its subtitles in these two files shown on File explorer:

Today, 1st July, I have modified the subtitles (VTT file) adding some characters.

Date created shows the date those two files where created on my PC, 30th June 2020.
Date modified shows 1st of July 2020 for VTT file (fine, since I modified it).
Though the video file (MKV file) shows the 21st October 2018, which does not really make much sense...
Date shows the 21st October 2018 for MKV file. And 30th June 2020 for VTT file, same as Date created.

What do Date modified and Date show when files are copied/downloaded and not locally modified?

The "official" definitions are quite brief:

• Date Created: ( System.DateCreated )

The date and time the item was created on the file system where it is currently located. This property is automatically promoted by the file system. The Indexing Service friendly name is "create".

• Date modified: ( System.DateModified ):

The date and time of the last modification to the item. The Indexing Service friendly name is 'write'.

• Date: ( System.ItemDate ):

  The primary date of interest for an item. In the case of photos, for example, this property maps to System.Photo.DateTaken.

So the underlying property Date/ItemDate maps to will vary based on the type of file and presence or absence of optional date-related EXIF metadata -- i.e. for a photo, Date taken if it exists, oterwise Date acquired if it exists, otherwise Date created.