Created in version 2.1

Version 1.0.0 - 1.2.0:
MCreator 2025.2 and ModMonster on Youtube

Version 1.2.2 - 2.0:
Reddit: /Minecraft; /MinecraftCommands
Minecraft Wiki
Minecraft Forum
Youtube videos (I do not remember the names)

Version 2.1:
https://minecraft.wiki/w/Function_(Java_Edition)
https://minecraft.fandom.com/wiki/Target_selectors
https://www.youtube.com/watch?v=HJJb2s2fFFc (not what I was looking for, but quite a nice guy)
https://www.youtube.com/watch?v=GwRfluFO3Tk
https://www.youtube.com/watch?v=ALb1uqgOyBk
https://gaming.stackexchange.com/questions/310050/how-do-you-type-the-symbol-section-sign-in-minecraft
https://www.youtube.com/watch?v=h_wCyA0MIa4
https://www.reddit.com/r/MinecraftCommands/comments/b4enmm/how_can_i_track_player_kills_on_a_zombie_or/

Gemini AI gave me:
  In the advancement file
  "criteria": {
    "killed_zombies": {
      "trigger": "minecraft:impossible"
    }
  },
  "rewards": {
    "function": "achievements_plus:grant/zombie_hunter"
  },

  And tick.mcfuntion
  function achievements_plus:grant/zombie_hunter

  https://minecraft.wiki/w/Advancement_definition
  https://www.reddit.com/r/MinecraftCommands/comments/1jxrlye/cant_set_the_background_texture_of_custom/
  Thank you GalSergey, couldn't find this anywhere, it was changed on 1.21.2 as well from textures/block/<item>.png to block/<item>

  Changelog:
  Added the Slayer achievements tab (Currently tracking Zombie, Skeleton, Creeper, Spider and Enderman Kills)
  Moved the place of where the "String Age?" advancement is shown
  Added "glowing" subfolder to "others" and "stone_cutter" to "recipe" in "recipes_plus"
  All "glowing" recipes have only one common advancement unlocked by glowstone_dust, added glowing_ink to it as well