You posted a picture of a conversation on social media, where none of them have scientific sources for their claims. The B12 part is true, but the fact is humans got B12 naturally when we drank water directly from the streams and ate food which was dirty when we were gatherers and hunters.
And has it ever occured to you why animals have B12 in them? Because yes, they as us naturally get it when they graze outside, but the fact is that the majority of the animals we consume are kept indoors in horrible conditions and have B12 added to their food. The only difference is that vegans take their B12 direcly, not though an animal.
Not to mention that loads of meat eaters have B12 deficiency as well.