I have to agree with the others about the length of the project. It definitely takes a huge amount of time. I also did a 3-minutes-long animation which took me a year to finish but I was a highschool student back then with very limited free time and it was also my first one so it might doesn't count. But as an animator student we have to make 1-2-minutes-long animations in 3 months. Most of us can't finish them because there's just not enough time. So, when we CAN finish our films, it's because we're heavily sacrificing quality and we are over-simplyfying everything we can. Also, for our thesis film, we have triple the time (2 semesters and the time inbetween, aka 9 months) to make sure everyone can finish it and we are also working in groups, like 3-4 people or more.
It doesn't mean you have to give up but you do need to expect it to take a very long time which also means that it's harder to find someone to join. Unless you're having a huge budget to hire more artists (or a small studio) and to hire them in full-time. It means it'll get more expensive but as we all know, with more money you can make the process way faster so you don't have to wait ages for the finished product.