Ruby Rose is the main protagonist, the leader of Team RWBY, and the first character introduced in RWBY. Ruby's weapon of choice is her High-Caliber Sniper-Scythe (HCSS) known as Crescent Rose.
She first appeared in the "Red" Trailer released on November 5, 2012, in which she fought Beowolves. Her second appearance was at the end of the "Yellow" Trailer, greeting her sister, Yang Xiao Long, and asking what she was doing at The Club.
Ruby was picked as Team RWBY's leader by Ozpin likely due to her being younger than the others, including her own teammates.
A somewhat similar concept is why RWBY's "sibling" team JNPR had its leader as the least combat proeficient, Jaune Arc.
Due to a combination of her younger age and her speed-oriented combat-style Ruby is shown to struggle in high heels.
Her voice actress Lindsay is stated to have similar issues, especially in comparison to Max Kreumcke (as Lindsay themself confirms in Minecraft 168).
This disadvantage isn't shown to be present in RWBY: Grimm Eclipse if playing as Ruby in her dance outfit.
While Ruby is primarily inspired by Little Red Riding Hood, in a way she also alludes to Dorothy of The Wizard of Oz (another show constantly referenced by RWBY), a newcomer to a fantastical world who worn ruby slippers in the 1939 film.