Four billion years is a lot of time for that randomness (via selective pressure of the environment or of life itself) to produce tons of crazy results.
I do both, old stuff and new stuff depending on the mood. Lately I've been exploring some genres I didn't even know existed like medieval speed folk (Perkelt is a group I like) and Dungeon Synth (Fief is my favorite so far).
Veganism is mostly about reducing animal suffering. It also has a health angle but it's mostly about the ethics of killing animals when we can have a complete and healthy diet eating plant-based (plus fungi).
2 years of psychoanalysis, tons of books. But for real, everyone can benefit from psychoterapy, just be aware that there are a ton of different schools of thought.
There are tons of easy alternatives for vegetable protein, including good old lentils, beans, chickpeas, etc. You don't have to go out of your way to buy tempeh or gourmet vegetarian food.