Human brains literally developed from agriculture and cattle farming

If if this was true, this doesn’t prove that it is still necessary or even beneficial today. Humans did a lot of things in the past that would be seen as strange today (you already mentioned crusades for example). It does not follow that, just because “we did it in the past” means we still need to do it today.

meat consumption is a need for the majority of the planet

I don’t fully agree. Please give me circumstances where there would be a NEED for this.