An animal free diet is devoid of animal products; it's another term for a vegan diet.
People adopt animal-free diets for a variety of reasons (religious, ethical, environmental, health).
I focus my energy on the question of how to plan animal-free diets for optimal health and function. This partly involves facing certain problems/disadvantages of plant-based foods and identifying solutions.
There is an idea circulating in the vegan community that if one consumes enough calories from a variety of plant-based foods everything will fall into place. Unfortunately, this idea is out of step with reality. I strongly suspect poor planning often causes people to abandon vegan diets; as this can result in nutrient imbalances, lethargy, reduced function etc.
On the other hand, well-planned animal-free diets can meet all our nutrition needs and help us to thrive.