Putting on my early neolithic archaeologist hat, there are a lot of things that don't show up in art. The trend in the past decade has been that better methods and new inquiries are turning up even more evidence for early broad-spectrum plant use everywhere we look.
e.g.
https://doi.org/10.1038/s41467-020-14723-0
https://doi.org/10.1016/j.jhevol.2013.12.014
https://www.researchgate.net/publication/351402155_Diet_of_t...