I don't understand this argument at all. Did democrats just vote for Obama because he's black and they wanted to make up for slavery? Same absurd logic.
Obama ran to Hillary's left and the Iraq War issue in particular helped him and hurt her. That's really why he won the nomination. In the general election, his being black helped with black turnout, obviously, but the percentage of the black vote going to the Democratic nominee wasn't all that different then in the past.
Carson's an entirely different story because as mentioned a lot, he has no actual qualifications or stage presence. Do you really think a white man with the same story that said a lot of crazy talk that made him unelectable in the general, sleep walked his way through the debates and had no prior political experience would really be doing this well?
As for Republicans and being racists...well, the South was a long-time Democratic holdout until they felt betrayed by LBJ and the Civil Rights movement...so, yes, racists.
Ending affirmative action programs is racist and hurts blacks in particular.
Ending food stamp programs hurts minorities.
Enacting voting restrictions mostly targets minorities, etc.
Sorry, but their recent policy proposals towards issues such as the above and immigration are, in fact, racist. They'll do a great job at getting that angry white vote and coming up short by a mile in the Presidential election once again but the rest of the country knows better.