At the bottom of the skill chain is aura users as a whole. While every living being in RWBY technically has Aura, actually being able to utilize it for things such as defense, regen, and senses requires years of training and a high enough degree of martial skill (and yes you actually need martial skill for it) that only a small percentage of the population of the entire planet ever become skilled enough to utilize their aura. Of that small percentage, an even smaller percentage ever become skilled enough to manifest/control a Semblance (yes semblances are also skill-based). To reach this small percentage comes to the second half of the bottom of the chain: Almost every character worth their salt in RWBY has spent their entire life training in combat and can fight hordes of Grimm with little issue (Almost because Jaune exists). The entirety of the main cast of RWBY was initially enrolled at Beacon Academy, one of the most prestigious combat schools in the world, with almost everyone who was accepted there having been trained for almost their entire life to fight monsters, and each one that was not professionally trained requiring a skill display overseen by Ozpin, who has the composite skill of several thousand professional huntsmen that he accumulated over his immortal lifetime and trained with Kami, fought and killed Demon King Piccolo in his prime. Bann Belladonna learned every single martal arts as a pre-teen
Thats the baseline for skill in the verse.
Before the Beacon Arc Ruby had been personally trained by her uncle Qrow in combat and as a result she was noted as always excelling above her peers in combat training. At the start of the series Ruby was at a level of skill that even though she was two years away from being eligible to join Beacon she was admitted due her combat prowess impressing Ozpin, with him noting that she was already a master at wielding one of the most dangerous weapons ever designed. In combat Ruby is capable of taking on entire hordes of Grimm on her own and walking away without a scratch and utilizing the different functionalities of the Crescent Rose, such as the massive recoil from the rifle aspect of the weapon and the weapon's transformative capabilities, in tandem with each other and her Semblance in order to maintain an edge over her opponent. Basically every named character is around this level of skill in the early seasons.
Now for Velvet. Velvet is able to perfectly and instantly mimic the exact moves that she observes other people use in combat as well as utilize multiple different fighting styles simultaneously, both armed and unarmed. Thanks to Anesidora, Velvet is also able to copy fighting styles that utilize weapons, and she is able to wield the weapons that she copies just as effectively as their original user. To date that we know of, Velvet is able to simultaneously utilize the fighting styles and weapons of Ruby Rose, Yang Xiao Long, Weiss Schnee, Blake Belladonna, Nora Valkyrie, Sun Wukong, Penny Polendina, Coco Adel, Peter Port, Reese Chloris, Fox Alistar, Vega Bleu, Yatsuhashi Daichi, Russel Thrush, Roy Stallion, Neptune Vasilias, Brawnz Ni, Bartholomew Oobleck, Flynt Coal, Edward Caspian, and Scarlet David. Of note, every person listed spent their entire lives training in combat and several of them are professional huntsmen with decades of combat experience.
Moving up the chain we have Nebula Violette, who not only outmatched Velvet in a 1v1 test of martial arts skill, but was directly stated to be more skilled than Velvet in combat despite Velvet mixing numerous fighting styles to try to throw her off in their fight.
Above her is Pyrrha Nikos, the skill god of the Beacon Arc. Pyrrha is one of the most skilled students at Beacon Academy, having won every combat tournament she has entered since she was a pre-teen due to both her mastery of combat and mastery of her semblance, being able to apply it in combat completely undetected and having done so in almost every fight she's been in for over a decade, doing so with such skill and precision that she has lead many to believe she is untouchable and invincible as no one has been able to even land a blow on her in her combat career. Even without her semblance she has shown the ability to quickly and easily adapt to her combat situation and analyze her opponents while fighting and changing tactics to suit the situation she is in. She has shown extreme accuracy, being able to hit moving targets from hundreds of meters away and strike vital weak points on an opponent mid-combat both with and without the aid of her semblance. She is also highly skilled at using her weapon's multiple forms in combat, being able to switch between forms several times in rapid succession to both deliver rapid attacks and counter others simultaneously.
