1. What you see on Tumblr is a minority of people.
2. You are displaying confirmation bias and only seeing the even smaller minority of examples which confirm your beliefs.
3. Women can post whatever they want online but that doesn't reflect reality.
4. As someone who lives in the real world and has seen what women actually respond to, believe me: your race doesn't matter.
As long as you are a normal looking guy, the only person who your race will matter to is yourself. Your own limiting belief will sabotage any interaction you have. Yes, there are SOME women that will reject you purely for your appearance (and your ethnicity plays into that) but the amount is relatively small.
To put it into context, imagine you talk to 1,000 women while having good grooming, fashion, being fit, having decent social skills and social intuition, and enough money to go out and do stuff/have your own place and car.
The amount of women who will be down to have sex with you out of that 1,000 might be 50, lets say (this is a purely arbitrary number, in reality it might be more or less depending on many, many factors which we can't even begin to account for). Out of that 50, maybe one or two will be disgusted with your race. Those women you didnt want, anyway.
That still leaves you dozens of hot girls.
It's all entirely a numbers game, and if you're doing everything else right, having a negligible decrease in the amount of women you can theoretically have sex with shouldn't matter, because you'd still be getting more than enough.
That's really all it comes down to. There is no magic pill and no one thing to blame all your problems on, but many people fall into this trap of blaming their race/sex/looks for their female troubles, because it's easier to wave one's hand and dismiss things as being not your fault, instead of taking some self-responsibility and reflecting on one's life.
It's a lot harder to actually acknowledge one has problems and work to improve.