Custom mob models aren't compiling properly

I am trying to add my first custom mob abd I'm having issues with model not compiling at all. Would be really happy to resolve this issue.

I am following NorthWestTrees Gaming tutorial series on Blockbench from 2 years ago and I have followed everything corectly, no uppercase letters or spaces in naming, corect export, texturing and mapping and other stuff. But when I put my model into Mcreator and try to make a mob with it, I get so many errors from console (The whole error message is in the pastebin link bellow). Anyone know what might be the issue? I'm using Mcreator 2021.2 version 1.16.

https://pastebin.com/bx3hh6Q7 (trying to make chicken model)

https://pastebin.com/jVQgYY02 (another attemt, was making a simple amogus model with all the same steps from before)

I want to mention that I'm relly not good in understanding actual code, so if it's some easy to resolve issue then my apologies for making this post.