Nice, I thought the Ring was something that was way too hard to code for it to work.
It would have required a complete engine rewrite. Which seems to be what we have here. I can't say it's what I would have done - a lot of work when into a huge number of details. I assume that the engine rewrite wasn't just done to add the ring item.
After working for so long on Indie Brawl, I gained an appreciation for all the details that need to be considered in a fighting game (even a relatively simple one). Before you get too much further, I want to make sure you understand the amount of work it would take to get the new build to the state of the old build. I wouldn't expect it to reach that point for at least a year. I'm not saying a rewrite is the wrong decision (I know how much bad code is still in the old build), but it's going to be a huge commitment.
Using Naija in the old build, if you use vA, you can influence her movement left or right, and, after the first few frames, you can also cancel the attack into another. vA causes a small amount of upward knockback, so it can be easily chained into another attack. vA is too slow and hits too low to be chained into itself. vA is a completely different attack if used in the air. If you use A on the ground, the attack propels her slightly forward. If used in the air, she maintains her current speed. In the air, A comes out more quickly, and she keeps her leg extended for a longer time (so it's easier to hit with the attack while moving). If she hits on the first frame of the kick, the attack is more powerful. The attack ends up being slower in the air, so it takes some time before another attack can be used. Both attacks had their damage, speed, and knockback adjusted many times to make sure they were reasonably balanced, as a result of substantial playtesting. It took a lot of work, and these were two of the simplest attacks. There were over 80 attacks, not to mention the items, stages and support characters. Just make sure that a complete engine rewrite is worth the huge amount of effort involved.
A few specific issues:
-You should have to press the attack button once for each attack/jump, instead of just being able to hold the attack button (or the jump button). You should not be able to double-jump more than once.
-Every attack in the new build completely halts your momentum. Most attacks in the old build maintain your momentum, which is especially important for the feel of aerial attacks. Other attacks would subtly change your momentum. For example, Naija's kick would propel you slightly forward when on the ground.
-It looks like you added the animations posted here without editing them, so the range and speed of the attacks will be unbalanced. In the old build, the animations were modified so that the attacks were reasonably balanced. And the animations will be different if the attack is executed while in the air, or if one attack is cancelled into another. For example, Naija's >A needs some cooldown, and her vA is way too slow relative to her other attacks (which are probably too fast).