wowow! i love these animations they are so trippy^^ awesome studies too!!

Wow you can tell you really understand the form of that body, it almost looks rotoscoped when it turns. Very impressive! Gets a bit sketchy towards the end but who can blame you that's a lot of frames haha

Back to ovals I see The roll could still use some work. Right now, it's more like it rolls onto its other point, then moves itself again, rather than being carried by some momentum. You could have also shown a little more force in it initially tossing itself into the first roll, to show the power needed to make it back up onto the other point.

As the the diving board, awesome! Great weight, great emphasis, I really like the mid-air hang (gotta build that anticipation!) and the slight pause as the board bends down. The following quick 2-3 frames of squiggles to represent it flying off the screen are also well done to show the speed the oval has flown away at, whereas in your previous animation with the bouncing ball, the ball stays on the ground a lot more.

In the previous animation, you had the mid-air emphasis right, but you spent too many frames with the ball touching the ground and shifting in momentum. It makes the resulting bounce back up feel like it should be much, much higher, since it takes a significant amount of force to squish a solid object, and that force is then transferred back. If you want a good example of how balls react to impact, watch some videos of tennis balls bouncing and being hit in slow motion. If it doesn't have much force, it won't deform much. If it has a lot of force being applied to it (speed, getting hit by a racket, etc.), it will flatten and stretch.

Your are doing great with your animation studies! One thing though about the ball jumping of a ledge. I get the feeling that when the ball hits the edge, it should just fall off (or do a gradual fall a bit further forward). This is because it ends up a bit too much off the edge, causing the center of mass to be on thin air.
I took a closer look at one of your animations and noticed that it is about 40 - 50 frames. How long does it take you to make one?
And also, are all those thumbnails done from imagination? They look really great for having been done in a short time, I should probably try to do something like that myself sometime

Another good improvement with the ovals and balls. One warning I'd give you with the three bouncing balls is to watch the height of each successive bounce. The initial bounce gives the viewer an idea of the material based on how much of the height the ball drops from is regained, and the percentage then can remain pretty stable.

So the ball will (roughly) always reach the same percentage of its previous drop height. your first ball shows this enough, getting back less than 10% of the initial drop height in the first bounce, and then barely even getting off the ground again after. Your second ball, however, breaks this rule. It bounces to 60% of its starting height, then to about 80-90% of the new drop height, then repeating some amount closer to 70%.

then your final ball loses a tiny bit of height, loses a bit more, then regains some height. Losing a very small amount of height is no problem, since rubber balls maintain most of their height each bounce, but regaining some height is impossible without intervention (such as it not actually being a bounce, but a character jumping repeatedly, at which point the inconsistency is welcomed).

As for your latest oval, I love everything about it up until the end when it eventually bounces straight up into the air after face planting. The issue I have with it is that if it's a character controlling itself, then it's bouncing itself back up after falling (which is fine), but it does so very quickly after falling, which means that it wouldn't actually lose all of that momentum. When jumping back up, it should have continued in a small arc towards the right of the screen, thanks to the force in that direction from throwing itself beyond the threshold of the oval tip.

I really love animation, and between studying it and physics I got a really solid understanding of how to make something animated look and feel realistic enough. I was never a fantastic animator back when I practiced, but boy could I make balls bounce and move around. They're the best practice, I find, for learning weight, momentum, pacing, and emphasis. These are the essentials which allow you to make an animation look real, but also push that realism into the epic. If you have one character jumping onto another, the "real" would technically be a very straight forward jump. If you wanted to stylize and make the jump important, you could have the character jump up, slow mid-air, then fall down atop the other. I wish I could pull up the old tutorials I used to learn all this stuff for you, but the website they were once on has long since been destroyed.

A ball only deforms if it's travelling/hitting something at a very high speed, and is also a material capable of deforming (such as a tennis ball, because tennis balls are hollow).

Anyway, if you're wondering why they look off, it's because of two factors. One is a misunderstanding of how an object reacts when it hits something (deformation is one way an object reacts, but it's not the most common. It's mostly when two forces are fighting against each other and compression is possible that you find deformation occur). Your balls hit the ground, but then they're sticking there for a number of frames. when a ball hits the ground, all of its force goes into the ground, and the ground then returns an equal, opposite force (Newton's 3rd law). So when it collides with the ground, it loses all of its force, thus there's nothing making it push down anymore, and it also receives the force from the ground, so it begins immediately shooting back up. Even with a deformation, the compression and expansion (squish and return to normal shape) is very fast. So your 4th ball down the line makes sense. It has a ton of speed, but notice how you also made it only compress for a single frame, and after that it shot back up with high speed. That's proper! The others spend a lot of time squishing against the ground, when they don't even actually need the actions.

The other issue is your spacing. How you've spaced out the motion of the ball doesn't fit nature properly, specifically the force of gravity on a ball. Gravity is a constant force, and it's the only reason a ball slowly loses speed as it travels upwards, and the only reason the ball then falls back down. What this means is that the rate at which the ball decelerates while flying upwards is about the same as how quickly it accelerates downwards.

Because the spacing of your balls is uneven, where they suddenly start picking up speed and flying downwards after a slow deceleration to a rest mid-air, it makes the tempo very hard to read.

I dug around a bunch through videos and tutorials on the community site of where all the animators I used to follow moved to, and although I didn't find the series I was talking about previously, I did find a great TED video on animation, specifically timing and spacing (the time you give something and how you move an object across frames). It covers a lot of what I've tried to teach you, though it doesn't focus on the more stylistic lessons like time spent as a way of showing effort or importance, and I think you'd really get a lot out of it. It especially helps since it's all visual, and I haven't provided you with any images throughout all my posts. Enjoy.