• Frostmint and Limestone spears have an infinite amount of durability (They should have a finite amount of durability, like tridents)
• Frostmint Spears and Limestone spears are able to break blocks in creative mode, despite being a weapon. Other weapons like Primitive Clubs can also do this

• Frostmint and Limestone spears have an infinite amount of durability (They should have a finite amount of durability, like tridents)

Frostmint spears can stack, so they don't have durability. The fact that they can be easily crafted might also be a reason. This is similar to arrows, which have no durability and can stack. The same can be observed with Limestone Spears. Tridents, on the other hand, are difficult to obtain and are not usually held in multiples, so they cannot stack and have durability.

• Frostmint Spears and Limestone spears are able to break blocks in creative mode, despite being a weapon. Other weapons like Primitive Clubs can also do this

I agree. Although axes and pickaxes have attack power, they can break blocks in creative mode. I believe this is because they are tools suited for breaking certain blocks like stone or wood. If tools like the Sharpened Candy Cane, Ortholance, Extinction Spear, and Primitive Clubs are not suitable for breaking blocks, it makes sense that they cannot break blocks in creative mode, similar to the Trident.

(This is a long written comment. sry.)