In regards to testing, maybe a modded DF with elves, humans, goblins and kobolds removed would increase the chances of animal person visitors.
Similarly, wasn't there a way you could give a creature a natural talent/predisposition for a skill in the raws? Would that automatically make them display a profession graphic?
That's a good idea and probably worth a shot.
I don't have the answers to your last two questions.
@Quiet-SunMy list is combination of verified professions that have been present since 2D DF, additional ones that came in various updates, the old wiki discussion pages before CLA took on the momentous task of organizing it all into actual pages for the wiki, looking at other definition files, and guesswork. I have left professions that I have not been able to verify (and noted them as such), but that are referenced in various places. There are also professions that previously existed that I leave in because Toady has put back removed professions in the past.
Like a lot of things in DF, there are exceptions and odd inconsistency (e.g. ANIMATED and GHOST are "professions"). Tiles can be defined by not just creature or profession, but by skill or assigned job. For example, a unit's skill level means nothing if you assign them to be a TAVERN_KEEPER or the CAPTAIN_OF_THE_GUARD. On the other hand, someone in your military that is a MASTER_SWORDSMAN doesn't care that you assigned him to the crossbow squad and never allowed him to have a sword as part of his uniform. Until another weapon skill exceed his sword skill - he will still be a MASTER_SWORDSMAN with a crossbow in his hand. Also, a general set of skills will provide you the generic status, rather than a specific one.
From CLA, Rydel, to my own definitions - we all organized them in a way that made sense to us. They are the same definitions, so they all work (aside from the ones CLA mentioned so you have a test case for your script). Your organization is also based on a way that made sense to you. The problem is inexperience in knowing the exceptions and inconsistency. So based on what I've shared so far, here is what I see wrong with your list.
In several cases you listed a general skill as the "default" correctly, although not considered DEFAULT in game. In other cases you've listed the wrong profession as the default. For instance, while the average skill levels in a variety of related skills would produce a FARMER and ENGINEER, COOK and MECHANIC are specific skills levels respectively to those generics. Also, nobles are specific titles - there is no generic (unless they are not define per Rydel's info) and they have nothing to do with skill levels.
I don't follow why DUKE is the default in your list. KING, KING_CONSORT, QUEEN_CONSORT don't exist as far as I know. They are covered by MONARCH and MONARCH_CONSORT. Again, I don't recall why I left QUEEN in there, because the elf QUEEN is the LEADER profession much like the PRINCESS position is actually defined by GENERAL for elves and I don't even see LEADER on your list. Nor do I see WARLORD or WARRIOR. And, PRIEST is not the default to DRUID - they are two different things.
PRISONER, COOK, MECHANIC, DOCTOR, DUKE, SHERIFF, MERCHANT and a few others are not default tiles. They are specific to those jobs/professions. MERCHANTS are not the default for DIPLOMAT or OUTPOST_LIAISON or SHOPKEEPER. PRISONER is not the default to SLAVE - again, these are different things in game.
Military: Aside from the assigned leadership positions - military tiles are based on skill level, much like ADVENTURER. And, ADVENTURER seems absent from your list entirely. DEFAULT, LAW_ENFORCE, TAX_ESCORT are assignments, SWORDSMAN and MASTER_SWORDSMAN are skill levels that exist together. Meaning you can have one tile for the DEFAULT WRESTLER that is completely different than the tile that represent the DEFAULT WRESTLER that is also LAW_ENFORCE.
I am sure there are more things I missed, but Rydel already pointed out that ALL profession defaults are DEFAULT.
Awhile back you said . . .
Since I'm so new to DF, I'm only familiarizing myself with the different sections so that's why I greatly appreciate your feedback.
Look, I don't want you to think I'm being sarcastic again or condescending or whatever because I am clarifying what I see to be a lot of misunderstanding on your end. I don't have all the answers, but I do see problems with your list. Also, I am still unsure about a few things. Like, did you understand why the red tiles are a problem(?) or did you understand what CLA was asking in regards to writing a script for the graphic set page(?) - something I believe would have great value.
I hope this information is helpful.
As a random suggestion, treating the animal people like the standard races wouldn't hurt, since defining things that may or may not exist won't cause errors in DF.