Why are they MIT licensed? That's a weird license to use for art assets. Why not Creative Commons?
- CC-By but include an extra note allowing people to omit attribution. This is hassle and may not be legally ok.
- CC0. This comes with other affordances you may not want
- Use some slightly inappropriate code licence like MIT
But MIT requires attribution as well:
> The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.