From a knowledge standpoint, I simply don’t know enough about nutrition to understand whether or not humans can be ‘maximally healthy’ on a vegetarian or vegan or pescatarian or w/e diet.
According to science, a whole-food, plant-based diet is basically the healthiest way to eat. You would need to supplement vitamin B12, but that’s it (and it’s very easy to do that). So from a health perspective, there is really no point against a vegan diet.
If you are interested in the morality of meat / veganism I highly recommend the debate videos by Ed Winters on Youtube where he talks to people about why they’re not vegan and it’s very respectful and also insightful. Like this one: www.youtube.com/watch?v=hdqAyFhWL2s (some are way more controversial though, this guy is already quite “vegan-positive”, still an interesting discussion)