My Greatest Rainbow

 I go by the philosophy that if you have enough parallels to fill up an entire 9 pocket page, that's enough for it to be considered as rainbow. I've put ones together so far for David Garrard (2008 Score), Nikolaj Ehlers (2020 Platinum) and Yermin Mercedes (2021 Prizm and Mosaic). While I'm sure all of those folks are fine people, in terms of historical magnitude, they're nowhere close to:

Frederick Douglass. 

For the 4th of July/250th this year, Upper Deck e-pack released a historical set perfectly timed for the celebrations. One member of the base set was Frederick Douglass, and being e-pack, getting 9 of the cards 

Going clockwise from the top left, there's the Pride Plus, the Bottle Rocket /599, the Red Patterned Foilboard, Patterned Foilboard, Pride, Independence /199, Uncle Sam /299, and Glory.  In the middle is the Crystal Clear American Variant. Which is a thick acetate that you have to hold to the light to see through.

Since the base card is only combinable, there really isn't a physical base card for the set. Pride is probably the closest thing to it, going by # of cards available on epack/COMC.

And let's put myself in Douglass double digits for this post with a 2009 American Heritage entry as well. 

There you have it!