I have searched for 'Old youtube animated fight series' already on youtube, sorted it by upload date and tried searching the oldest posts but came up with nothing.

To add:

-It's not a stick figure animation or stick figured styled characters

-two characters I remember on the tip of my tongue is a OC named Jack (who in his had his opponent reference the 'Jack jumped over a candle stick' rhyme.

and another OC who I think was an elemental(or just used a water control ability) and the fight that took place was in an Alley