Stock footage films can be very useful for creating films with often global breath without having to break the bank in commissioning multiple live action shoots. But there are certain limitations to consider. With stock footage you're not just limited by what footage already exists, but also by what footage sits well together, as there are infinite combinations of style and quality. For this reason, you'll need a solid plan and crucially, the freedom to let the project evolve during production. You'll also need a quality director, producer, visual researcher, editor, colourist, and sound designer to make a pool of stock footage come together to form a cohesive film with a clear message.
Apart from highly curated shot selection, animation and kinetic text are also useful devices for creating a thread to bind the film together.