To name just a few examples in each category for Native Americans:
Great Writer
Nezahualcoyotl (Aztec, Poet)
Francisco Hernández Arana Xajilá (Mayan, Historian)
Ah Bam (Mayan, Poet)
Pachacuti (currently the in-game Incan leader, but also a poet)
Sagoyewatha, aka Red Jacket (Iroquois, Orator)
Zitkala-Ša, (Dakota, Folklorist)
Luther Standing Bear, (Lakota, Memoirist)
Great Artist
Hasteen Klah (Navajo,
Tapestry Weaver)
Atsidi Sani (Navajo,
Silversmith)
Shaxʼsaani Kéekʼ, aka Jennie Thlunaut (Tlingit,
Chilkat Weaver)
Matȟó Wanáȟtake, aka Kicking Bear (Lakota,
Painter)
Da.a Xiigang, aka Charles Edenshaw (Haida,
Sculptor)
Nakapenkem, aka Mungo Martin (Kwakwaka'wakw,
Sculptor / Painter)
Great Musicians
Judy Trejo (Shoshone,
Singer)
Walker Calhoun (Cherokee,
Singer)
Pteskawin, aka White Buffalo Calf Woman (Lakota, Composer of the Calumet Dance, which I can't find a good sample of at the moment)
Pukawiss (the mythic creator of
the Hoop Dance)
There are a lot of other traditional dances that could be included as Great Music because of their cultural significance, but I'm a harder time picking people to associate with them. Trejo and Calhoun were chosen for preserving those songs; Pteskawin and Pukawiss were chosen for inventing theirs according to tradition. I'll probably have to do some digging to find someone for the Stomp Dance, the Crown Dance, and the Buffalo Dance, which would be the next three on my list.
In all the categories, just like the songs, I limited myself to people who invented, preserved, or particularly exemplified traditional art styles and who are known by name. There's a lot of art by regrettably unknown artists I would have loved to include, like
this Mississippian copper plaque or the authors of the
Popul Vuh or the
Xajoj Tun. I also didn't include more recent Native artists continuing to expand and adapt Native artistic traditions, so we miss out on Sherman Alexie,
Jerod Impichchaachaaha' Tate, and
Roxanne Swentzell, among others