But it's hard not to be a little sad at the fact that, insofar as I am perceived as male, I am by default perceived as an unlovable and dangerous subhuman monster

That's not what the meme is about or saying lol, it's pointing out the fact that to most women, the average man is probably more dangerous than a bear. Patriarchal violence. I do think the meme is a bit un-nuanced maybe, like a product of liberal "feminism", but it makes a good point.

but is "not wanting to be a man" enough to pull the trigger on a medical transition? It feels like I should be running TOWARDS something I want, not just AWAY from something I hate.

Sure, why not? You don't have to do anything super drastic about it either. Honestly early in my transition, my identity was mostly defined by the fact that I'd die on testosterone. I did not want that, I did not want to be a man. I didn't immediately become a woman as a result, either.

Also if "get a hobby, but trans" feels better than man-advice to you, well =)

If you asked me how I imagine myself inside, the honest and silly answer is that I feel like a "Scrimblo Bimblo"-type genderless cartoon/video game character.

Sounds valid as fuck to me, perhaps you are some nifty variety of nonbinary or grayish/agender femme? Many cool possibilities!! It does seem to me like, above all else "man" is not for you ❤

It kinda bugs me that the transition/gender discussion is so binary, I think it's causing a lot of trouble for you.