Here's a quick look at just some of the diverse art you will find in the Level Up: Advanced 5th Edition hardcover rulebooks. Some of these are from the Core Rulebook, and others are from the Monstrous Menagerie.
Halfling (Erik Davis-Helm)
Tiefling (Erik Davis-Helm)
Ranger (Mark Bulahao)
Aboleth (Kim Van Deun)
Faerie (Egil Thompson)
Cambion (Yihyoung Li)
Hobgoblin (Vinicius Wemeck)
Basilisk (Sade)
Chimera (Guilherme Sommermeyer)
Behir (Guilherme Sommermeyer)
Halfling (Erik Davis-Helm)
Tiefling (Erik Davis-Helm)
Ranger (Mark Bulahao)
Aboleth (Kim Van Deun)
Faerie (Egil Thompson)
Cambion (Yihyoung Li)
Hobgoblin (Vinicius Wemeck)
Basilisk (Sade)
Chimera (Guilherme Sommermeyer)
Behir (Guilherme Sommermeyer)