Thank you for your review, I appreciate it.
I am currently planning on adding support for 1.16 but eventually, I plan on adding support for 1.8.
I would recommend using a plugin such as this one:
https://www.spigotmc.org/resources/oldcombatmechanics-disable-1-9-hit-cooldown.19510/, to get the old combat features rather than using a 6-year-old version of the game.