Few ideas for new Origins:

Sheepling - Half Sheep, Half Human

[Activated Power: Eating Grass]

Pros:

• Can instantaneously eat grass, which includes Grass Blocks (turning them into Dirt Blocks), Grass and Tall Grass;

• This makes it restore some Saturation

• You can eat Wheat without a need for crafting it into a bread

• Your Body grows wool which you can shave using shears;
   - You seem to grow more wool after eating;

  • You can Dye yourself while covered in Wool;
      - Doing so you permanently set color of your future wool blocks, until you Dye yourself again;

• Being covered in wool gives you small natural protection from damage

Cons:

• You can't produce wool while wearing armor (Except Boots and Helmet);

• You can't wear armor while covered in wool (Except Boots and Helmet);

• You take x2 damage from fire if you are covered in Wool

• You can't eat meat;

• You have 2 less maximum hearts of health

Slimeborn - Half Slime, Half Human

Pros:
[Activated Power: Hyper Jump]

• Your character get's thrown in the direction it's looking at but only if it touches a ground

• You can't take fall damage

• You have to die twice in quick succession before ACTUALLY dying (and having to respawn again)
   - After you die, you separate into two smaller Slimeborns, one of which you control, other is following you and helping with fights;
    - After a bit of time you can connect to your other half to form your full-self, or after even more time you may grow back to your full-self.

Neutral:

• Almost all blocks acts like Slimeblock, making you bounce of surfaces and walk on them very slowly

• You are transfluent... but also slightly green.

• Items in your inventory may be visible inside of you

Cons:

• You have 2 less maximum Hearts of health while you are "Whole"
   - You and your other Half have 4 Hearts of health each while separated

Illager - Pillager of Villages:

Pros:
[No activatable abilities]

• Illagers are passive towards you
   + You start a game in a Illager Outpost

• Ravagers are passive towards you and can be tamed
   + You can Ride Ravagers

• You deal x2 damage from Crossbows

• Villagers and Traveling Traders killed by you drop various loot

Cons:

• Villagers and Traveling Traders don't want to trade with you and they actively run from you

• Iron and Snow Golems are hostile towards you

• You can't summon Iron or Snow Golems

• Your personal crafting grid is reduced to 1x1

Last few suggestions I would give will be for already existing Origin: Arachnid.

While it's ability is activated (so... when it can climb any block), Webs should act as Vines, so player can climb Webs and create self sustaining "ladders" without having to place other blocks to do so.
While you CAN use any block as a ladder, it's more difficult to climb down.
Webs could also act as a safe net by slowing down your fall.
Finally - you could turn placed String into a Web when you right click it with another string. That would expand on the arachnid even more. To cancel turning String into Web, you could (choose which version you prefer) hold shift or creating Webs would be possible only when you turn your climbing abilities ON.

Also - Blazeborns are immune to Poison and Hunger Effects, but Arachnids aren't immune to Poison?
What if Arachnid took no damage from being Poisoned, but while being under the effect it would apply Poisonous on attacked targets? Kinda like Blazeborn being stronger when on fire.
That would give an interesting twist on effect otherwise considered a negative and some might even use drinking potions of Poison as a way to buff itself.
No need to even make potions in early game - Spider Eyes inflict poison on you, so you could use those as a way to activate your poisonous abilities.
Also - combining with your Class extension: Imagine Cleric Arachnid build where you use your overpowered enchanted gear and your overpowered Poison potions as an ultimate hunter build?

To make the character much more balanced I'm suggesting either taking away one more heart (Leaving it with just 6 Hearts) or giving it another unique disadvantage. Blind at day and/or near light sources? Weakness to Fire? There are many options to consider...

I hope you like ideas for the origins and that they would be balanced.
I post it there since... well, this post is super long to be posted on Curse Forge.

Here are some of my ideas:

Undead origin:

• [+] Other undead (including Withers) are passive to you.
• [+] You can summon zombies that fight for you whenever you take damage.
• [±] Potions of Harming and Healing have the opposite effect on you.
• [±] Regeneration and Poison effects have no effect on you.
• [-] You walk/run slower.
• [-] You burn in sunlight.
• [-] Villagers and Wandering Traders don't want to trade with you and they actively run from you.
• [-] Iron and Snow Golems are hostile towards you.
• [-] You sink in water and can't swim very well.

Illager origin:

• [+] Witches heal you with potions of Regeneration and Healing
• [±] In addition to already-proposed suggestions

Giant origin:

• [±] You are naturally 2.5 blocks tall. (2 blocks tall when sneaking)
• [+] You have more health than normal.
• [+] You break blocks faster.
• [+] You deal more melee damage.
• [+] Your inventory crafting grid is increased to 3x3.
• [+] You take less knockback from most mobs.
• [-] You exhaust much quicker.
• [-] Eating food restores less hunger for you.
• [-] Your tools and armor break twice as fast.
• [-] Either "You can't use elytra" or "You fall much quicker when gliding with elytra"
• [-] You can't wear regular armor.

Dwarf origin:

• [±] You are naturally 1.5 blocks tall. (1-1.25 blocks tall when sneaking)
• [+] You exhaust slightly slower.
• [+] You fall slightly slower when gliding with elytra.
• [+] Regular armor provides more protection.
• [-] You take more knockback from most mobs.
• [-] You have less health than normal.
• [-] You break blocks slower.
• [-] You have 9 less inventory slots.
• [-] Your reach is shorter.