I voted yes because Ava has the most important role among the 5 foretellers, and the movie shows her importance by giving her the most interactions with the others and the scene with Ephemer. I think she has a bit more screentime/dialogue lines.
Luxu's role is also very important to the plot but he's not supposed to interfere with the others so he has little screentime.
The poll choices are a bit lacking, though. For me it's the MoM who carries the whole movie, main character or not. But that's not what you asked... so yeah, it's Ava.
It's a similar situation to Final Fantasy VI. There's not a definite main character in that game but if one must be chosen it's Terra, with Celes as a close second.