Trying to find where to look - B19001A_001 is the total for white individuals (I think). Not sure if that's where to start. I'm using a very crude split (White alone, all others classified as non-white) - I know it's not accurate - but this is for a school assignment.
[For anyone who received an email with a previous response from me, please see this one instead. I hit "reply" prematurely before.]
Median incomes can be found in the set of tables starting with B19013. If you want mutually exclusive categories, then I'd recommend B19001H (which includes only people who identify as White and not Hispanic/Latino).
There's no corresponding table for everyone who identifies as Black/Indigenous/people of color. You could use the microdata (IPUMS-USA), but if you haven't worked with the raw data before, and/or need this data for areas with fewer than 100,000 people, and/or want to match the summary files, you can estimate this in a spreadsheet from the distribution of household incomes:
On that formula: it's easier to see this in an example than in a verbal description. I can't figure out a way to put a screenshot in this message, but it's in this presentation from a previous ACS Data Users conference. If that doesn't work, let me know and I can send it to you directly.