Your answers were not being downvoted because they were taboo or too diverse. Answers are going to be downvoted (and in extreme cases, removed) whether they are diverse or not, when they are poor quality, as they were here.
First: Beast Companions
The first was downvoted, with near certainty, because it failed the "Good Subjective, Bad Subjective" test. Those links point to the overall Stack policy on subjective questions, and the RPG Meta which hashes out our approach with it.
The gist of the policy is that some questions are subjective in nature, but this does not open them up for just free-form brainstorming of untested ideas. This policy is currently getting a lot of attention and policing from users, for reasons beyond the scope of this answer.
That this is the reason for the downvotes may or may not be obvious, since I think you're a recently joined user: There are currently no mentions in the comments to the question, or to your answer, so if you are not familiar with that policy I'm sure it was quite baffling. But that is almost certainly what it is.
Please note, after you review the policy, whether you agree with it or disagree with it, this question is not the place or method to challenge it.
Please note also that this answer is of sufficiently low quality just by vote counts that it may ended up removed anyway.
Second: Religiously Inflexible Players
This (I'm linking to the question, not the answer, since the answer is deleted) was not removed for Good Subjective, Bad Subjective reasons-- I can see the revision history and it started out describing an actual example of your answer in play.
Then, when asked to follow up on that with details on how it worked, you updated with what I assume was a sarcastic satire of the player's beliefs, which I will not describe here, but was at the least disrespectful to your player and anyone with adjacent beliefs, and arguably abusive. (And since the answer ended up deleted as abusive by more than just mod action, the argument is strong.)
If you really, honestly need a written down rule that you broke, see this site-wide code of conduct, specifically, "No subtle put downs." (Although the put down wasn't that subtle.) I would also consider this, from the same page, alienation based on religion.
I do not consider "Don't engage in put downs, and don't be abusive" to be a matter of taboo. It is a matter of site policy reinforcing civil behavior amongst (ironically) diverse populations of users.
I note in passing that this question spawned quite a few answers that were later deleted: Four of them were deleted by their owners after being challenged for additional evidence, one by votes after being challenged for additional evidence, one as spam, and one (yours) by vote for being abusive.
Objectively speaking, you are not being singled out, here, at all. Certainly not on the basis of your diversity.