I'm looking for novels where the protagonist gains a unique system that allows them to copy or absorb attributes from others. Are there any like that?

Absolutely! That's a really popular trope in web novels, and there are tons of great options that fit what you're looking for. The idea of a protagonist gaining a system that lets them copy or absorb attributes from others opens up so many interesting power-scaling possibilities.

One of the most well-known examples in this vein is "Solo Leveling." While not strictly copying attributes, the protagonist, Sung Jinwoo, gains a unique system that allows him to level up by defeating monsters and completing quests, essentially absorbing their power and skills. He also has the ability to create shadows from defeated enemies, which he can then command, giving him a diverse array of abilities derived from others. It's a fantastic journey of a weak individual becoming incredibly powerful through this system.

Another series you might enjoy is "Reverend Insanity." This one is much darker and more morally grey. The protagonist, Fang Yuan, uses a unique "Gu" system, which are essentially parasitic insects that grant him various abilities. He cultivates these Gu by absorbing the essence and even the souls of others, effectively copying or inheriting their skills and knowledge. It's a brutal but compelling story about ambition and survival.

For something a bit lighter, "The Novel's Extra" features a protagonist who wakes up inside the novel he was writing, and he gains a system that allows him to acquire 'traits' from characters within the story by interacting with them or fulfilling certain conditions. This often involves him understanding and then replicating their unique skills or innate talents. It's a meta-narrative with a fun twist on the attribute absorption idea.

You might also find "Myriad Cultivation System" interesting. In this novel, the protagonist gains a system that allows him to cultivate and absorb the cultivation bases and techniques of others he defeats. It's a classic power fantasy where he rises through the ranks by continuously strengthening himself through these absorbed abilities.

These are just a few to get you started, but the "system" genre, especially with attribute copying or absorption, is vast. You'll find variations on this theme in many cultivation, fantasy, and even some sci-fi web novels. Happy reading on Novelblur!