Ooh yes now this is a change I'd like to see! I have some thoughts on all of the proposed boards + a few other thoughts of my own, so I'll work on organizing them based on each board proposed:
Should the board suggestions remain as they are in some capacity:
Human/Humanoid Humans and human-like species (vampires etc)This would be a good board to implement! However, just based on the target demographic that chicken smoothie attracts, there aren't a massive amount of human artists as it is. I personally think that anthros should be included in this category for consolidation's sake (especially since bipedal anthros can look like a range of things) but I understand that not everyone would have this same opinion. Though I definitely think this board (or some iteration of it) would be crucial to see on the final list of boards.
Animals Real animals (living or extinct)
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Fantasy/Made-Up Species/Anthro Fantasy, mythology, or otherwise fictional speciesI do agree with hannabun here, at least in part. I think that Animals (fantasy and real) should be in the same category. This is because there are a lot of areas of overlap-- for instance, where would fantasy dog or cat breeds come in? Where would historically inaccurate dinos be put?)-- and it would cause confusion for people looking for where to put their art. I think this theoretically combined board could be renamed to "Feral Art", or "Animals and Feral Art" or something like that. I think mythology should be pulled out of the specific name for the "Animals Art" board since mythology can technically be seen across any range of these categories (not just fantasy species; human/humanoid characters could be derived from mythology, for instance)
Fandom/Fanart Anything from a fandom - e.g. cartoons, games, booksI definitely think this should be implemented. I don't have many thoughts about this, but I think it'd put some responsibility on the poster to make sure that when they post, the drawing's clearly demonstrated as fanart rather than OC content. And when the oekaki moderators are moderating, they need to not incorrectly categorize a fan animal (say Disney's Bolt, for instance) as a drawing of an OC or regular animal. Also, I'm assuming this board would include CS fanart?
Landscapes/Scenery E.g. fields, forests, extraterrestrial, architecture
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Objects/Other Objects and anything else which doesn't fit the above categoriesI personally believe that these two boards should be consolidated, and I agree with bee on the suggestion of combining these two. Maybe into something that's more general, like Landscape, Objects, and Other, or something along those lines? I think there's too thin of a line between landscapes and objects for them to be separate boards. So, say someone draws a planet on a transparent/white background. Would that be a landscape drawing of a planet, or just an object? Same with a single tree. I think it could be argued both ways (depending on composition), which would bring confusion if these boards were kept separate.
I put the "Other" in the proposed title to possibly account for more abstract art that couldn't be easily defined as a landscape or an object. This could include even simple text art as well. I do also think that text art should be categorized on CS appropriately, and not just locked or deleted because it doesn't have a defined objective subject.
Reference Sheets For your original charactersI definitely think this needs to be implemented. This is just personal opinion and I recognize that everyone might not agree, but having a space dedicated to character ref sheets would be so, so useful! Would this include adoptable species references (as in, separates of adoptable characters)? If this doesn't include adopt species I definitely think that having a subboard in the "Created Pets" section for adopt species references would be perfect for anyone looking to add a reference of a character they've adopted/bought/etc. from the Adoptable Oekaki board. This would be alongside the ref sheets board. That way, the Created Pets section can be limited to just created pets people can browse through, instead of already owned designs that users want references of mixed in.
Combo for pieces that fit into multiple categories e.g. featuring both a human and animal characterI agree with hannabun again here. Most people may very well end up posting in the combo section due to the assumption that they aren't sure if their art belongs in a specific place. This board suggestion might be too vague in some aspects? Like, would a combo mean both a landscape + a human/animal/etc. subject? Do fully rendered pieces with detailed backgrounds and multiple subjects-- maybe in this case, just dogs-- go here? Or would they fall under animals?
Other Suggestions (not really limited to the proposed boards, but just some things I think would also be good to see!)
A tagging system. I don't know how feasible this is with CS's board system, but I feel like a dedicated tagging system would solve so many of these problems. Resorting the boards definitely helps the people posting, but what about on the observer's end? If people perusing the oekaki boards are looking for something specific, then they can just filter by tags to find what they want so much faster! This would be perfect for sorting by categories, art sales, and so much more. If this is possible in the near future, then I would love to see some form of a tagging system for art.
I think that sketches and experiments should stay, but be renamed(?). Maybe into something like sketches and wips? I do still think there should be a board for "scraps" so to speak, but the board's new rules should also make it clearly defined what a sketch would be. I agree with others that a sketch should be defined as something loose with minimal coloring, but it would also be important not to distinguish something with just lineart (or b+w) as a sketch even though it may be finished in the artist's eyes.
More specific Adoptable Oekaki boards! I agree with lucifer here; Alongside the sub board for created pets, there really should be more specificity for the Adoptable Oekaki board too, especially since some users are only interested in one type of species over another. Breaking down the Adoptable Oekaki boards into Fantasy|Realistic|One offs would be a good first step. Especially for the rise of interest in animal ARPGs.
Break Up the Comics and Series Board. The board is less about actual comics and more about "Ask me" threads with people's characters. Maybe break up this board into simply "Comics" and "Ask the character" boards.
Make an Artist Search board for Adoptable Oekaki. This would make a better distinction within competitions; maybe make this its own sub-board in Adoptable Oekaki?