This isn't something unique to Libs though, and in fact chuds do it more.

White Jesus, White Aryans, White Native Americans (we wuz solutreans n shiet) are all the same thing as Hamilton, they've just been repeated for so long that nobody even thinks twice about them (other than the white Native Americans bit, that one isn't really mainstream)

Chuds pretend the past is white in order to bolster their racial morale
Libs pretend the past is non-white in order to bolster their national morale