Ok this is beginners level and it's nice to see someone trying to improve, 3D rules.
So, my opinion for voice acting is keep training, you are on the right track, just go through it with time, practice and attempts to convey emotion in a way it feels natural for your character, you will attain ever improving acting.
Animation, it needs some more mid frames to carry out moves more naturally, consider acceleration (start slow,pick up speed, speed down, reach still pose) to make moves more organic and it will fell much better.
Personally I believe that if a camera moves around the model and the background image doesn't move with it's not a functional background (5:47 is a no no), way to fix, create a model wall and paint the png in it, or a cylinder panorama, this is how movies now a days do it on some scenes, except it's a recording put on a green screen (Avengers behind the scenes teaches lots of interesting info on how to do movie "awesomeness", other Marvel movies also apply).
Shadows are awesome with creating reality, if there were shadows of trees in the forest it would look so good, seeing the shadow of elements that aren't in the scene increases realism, also would be cool if dirt was at least painted at the bottom of trees, grass and flowers.
NITPICKING TIME (only do this because I love to help determined people to improve and want them to take over the world with the skills I've helped them to unlock)
Intro doesn't look underwater because there ain't no dark blue shade in the camera (solved by after editing on a video editor, or putting a shader in the cam if your 3D recording program allows it).
0:44, not enough wet sand (brown between sand and water).
0:52, Nesy isn't walking on anything, viewers can tell.
1:05, if it went silent on the transition, then Nesy mentions finding the shellfish while in scene, it would have felt less rushed, in addition it fells more dramatic if she stays head down, "unless", pause, smile, "it was them".
1:18, more silent moment was needed.
1:40, same float walk as 0:52.
1:47, water background or blue watery plane over amnesic girl would have held the scene together.
1:49, missing scene were WE find out that guy was spying, and a surprised face opportunity
2:00, the green effect made me lose the eye color change.
2:03, missed opportunity for ULTRA SURPRISE FACE for that witch is a greater than the previous realization (hands cover mouth or holding head, mouth almost screaming, very goofy ), but at least we got a surprise face.
2:22 there should be a view of the water there at some angle, (unless I'm not seeing two woman on a rock in the beach, I understood it like that but there could be a confusing illusion that makes the girl think she's on space, maybe).
2:31 she is floating number 3.
2:38 I couldn't remember he was on a rock (because at that point, on first viewing, I was confused by the space spirits), as result it looked like he had descended from space itself on to Earth, kinda my bad, but if I could see the rock I would have remembered he was on a mountain/cliff, so it's avoidable goofiness on a serious moment, therefore I shall nitpick it.
Nice opening sequence and cool not commonly used font, this isn't quite serious but it's cool to share, making your on font ensures uniqueness and can help to create identity, but if it ain't as common as comic sans, it should work.
3:51 Ha, found it, see that neck movement, looks unnatural (RIGHT?), so that's were 4 frames of animated acceleration make that move less robotic.
4:14 Somebody broke a neck, that is a VERY crunchy sound for a hit, "That didn't go like I thought it would", now I've got to get rid of evidence.
4:34 More of robotic movement 'cause lack of acceleration.
4:41 I spy with my eye a frame that needs to be exorcised.
4:58 Hand grips look beater with open fist turning into closed fist and small arm pull back.
5:30 He walks in one direction and goes to another.
6:04 Fair game for the arms not being the perfect dive, but those legs are REALLY goofy, it would work if they got into a straight pose while getting into the water (it exists and now I shall acknowledge your skill to make it interact with characters, but why only here, there were other scenes begging for it).
6:21 Okay so, the light in this scene almost makes up for the lack of filter (or I'm dumb/can't tell and there was a filter in there), but at least one of two things is happening, it's to suave to noticeably change the camera or it isn't blurry enough, but honestly it's one of the most polished animations of the episode (nice faces tho, half for goofy and half for showing the CRAZY of the drama).
7:03 Look at that poor little tree in the background, it's begging for shadow, and wishing to look real.
7:43 THAT RIGHT THERE, those leafs, those HEROES, they made some seconds feel really forest, for a bit there was wind worked on to that world, and there was darkness and shadow, and it was awesome, I MEAN look at that girl, now I BELIEVE she saying a serious "okay" and that she is fighting for free will
7:47 Please, a silent moment would be perfect here.
7:47 That hole is to bright, it's okay not to show the character for a bit.
7:47 If the siren went from "sister" almost silent to mid term "sister" and then into a normal "sister", It would have been more climatic, it would feel like Nesy is fighting the fish lady and trying to say no to fish tail.
8:20 That knife didn't stab or cut, why, the blade wasn't aligned for either of those options,
but that could have been just a threat that scared her so much she had scream like that, now I DON'T want to know how she screams when things get actually violent.
8:28 Unintentional neck break is still funny for the second time.
8:34 Cool docks, just there isn't a good way to explain the light on the scene, the back is dark so it isn't the moon, there fore "they" decided to just let one specific lamppost on, exaggerating on the nitpicking in that one though.
8:42 Pelvic trust teleport, or the wood gate is a hologram (it's funny, in a dumb way, to make a "wosh" sound on the scene change).
THAT'S IT, I hope this helps your team in some way, giving some boost creativity or helped notice something you didn't understated on your on, this kinda took well over an hour so I hope that someone gets something out of this, well good luck on your series journey it can be fun, and if personalities are well developed people might get really attached to your story, but if that happens let me warn you the first sing of that possibly happening is when you care to what happens to your characters not because they are plot important but because you care about them and want to see they fulfill their journey. Try playing around developing fun identities a bit more than the "what we must do", like with Foamy The Squirrel, it isn't trying to be to animated, but what his fanbase (precious) enjoy is to listen to his a bit extreme and script developed opinion, if you can care not about an amnesiac girl, but about Nesy who has amnesia, then you've got a character.
Now I'm done, I need to stop writing this, it has been a bit compulsive after a while, but I really wanted the chance to help someone who wants to put effort into things and might have exaggerated go have fun in your journey I really hope I don't comment like this again at least for a little while.