Hello!!......all helpless millenials who have no mechanical knowledge,or, skills.....I have come to alleviate your IGNORANCE and PAIN !!!
The stock Samsung USB to mini USB cable that is included with the original charger " brick" has TINY metal contacts, which appear to be gold , but, are NOT. Upon close inspection with a jewelers 10x eyepiece, one can see discoloration , dirt, and wear on these tiny contact " strips" that needs to be cleaned to restore the original fast charging performance. I have an old spray can of "Tuner Cleaner" , which contains a fast evaporating solvent that was originally formulated to clean the dirty contacts on old TV tuners. All that was needed was a quick spray into the female ports on the " brick" and on the phone PLUS a small squirt on each male end of the cable. Then, while still wet....before the cleaner quickly evaporates......rapidlly connect and re-connect each male end into its appropriate female counterpart at least ten times per connector. Voila !!....the contacts are now CLEAN and fast charging is RESTORED !!!
"Occam's Razor" folks.....the simplest solution is usually the CORRECT solution.....clean the dirty contacts !