Malte brings up a good point. You would have to have a core team of people, and they would have to be dedicated to the project and be willing to compromise with one another. I've been on the ground floor on a lot of independent projects, and the main reason I've seen them abandoned is because the self-proclaimed 'director' disappears or loses interest. Having a creative 'team' at the head would help with that, but as Malte pointed out it might cause contention with other production members who weren't on the 'team,' and the team itself may fall to bickering and inaction. As for the contention, that might be solved by taking a democratic approach to production decisions. The heads would have to have the final say, but an open conversation and suggestion forum surrounding each potential choice might get rid of the bitterness factor that could arise in a more dictatorial system. As for the bickering and inaction... well, that's partly luck of the draw, partly team members being willing to police themselves and each other
Also, I happen to be an animator who knows a bit about film production

Are you planning on a feature length sequel? If so, plan on it taking many years to complete, and don't have high expectations as to the quality of the final product. Animation is a labor of love, and it is extremely time consuming. It is also very difficult to find animators who are willing to work for free, and, as you mentioned, most people's lives are very busy. Even a short scene could potentially take an animator months to complete.
I would suggest maybe tackling the project in shorter 'episodes.'
Keep in mind I am not trying to discourage you, either. Just being realistic
I think this is a very cool idea, and I would love to contribute if we come together and decide to take it wherever it goes.