Lucifer is (literally) white, but he isn’t White™
Other pieces of information that may be relevant (long-ish post ahead; scroll fast if you don’t care):
~ unusual stress / emphasis on words
~Traits (incredibly pale skin, blond hair, etc.) that are very evocative of albinism.
~ Vaggi, the other fallen angel we know about, canonically speaks Spanish, which sets a precedent that Angels Can Do That*.
* Human language (especially English) is often treated as an inexplicable given for nonhuman / fantasy species— due to the nature of existing as fictional constructs created by human people to communicate meaning to other human people— so by speaking multiple languages Vaggi is establishing that A.) this language is relevant in-universe, rather than simply existing as a matter of course for the viewer’s benefit, and B.) isn’t exclusively English.
~ Carmilla, the fallen Angel that we DON’T yet know about, also canonically speaks Spanish (and one of her children has alternating blonde streaks in her hair like the Morningstars do), but that’s probably a separate post of its own.
~ Alastor’s sinner form is noticeably paler than his human form, whereas Vox and Sir Pentious, both incredibly pale in life, both have skin which is literally black in the afterlife— so there are multiple precedents for skin color not telling the whole story about a character** (and, moreover, providing a deliberate misdirection).
** Side-note: ‘Skin color / appearance changing after death in a way that alters the way you perceive someone and affects your ability to deduce / infer information about them’ is also another point towards my ‘Hell is a Quarantine Aquarium’ interpretation. This is a known problem with many marine life-forms, and obviously complicates research. Also adds an interesting implication to that scene of Angel showing Husk the picture of the depressurized blobfish (whose iconic appearance is the result of being forcefully fished up from its properly-pressurized environment). But, again, that’s probably a separate post.
~ Sir Pentious’s skin goes from being black to blue once he ‘ascends’. Given the above instances of skin coloring decisions, I’m inclined to suspect that this is intentional and meaningful***.
*** ‘The showrunners are designing around Heaven’s palette’— boring. No sauce.
‘The showrunners are subtly establishing some kind of dystopian, in-universe whitewashing’ — NOW we’re talking. Why would this be the case. Who even benefits from this. What are the ramifications of a system like this. Fascinating approach.
‘Heaven and Hell are sentient entities, who are designing around their respective palettes’— the meta comedy potential is off the charts. The reason Alastor’s design has so much red is because Hell wanted the pale skin punishment and had to make him look hellish in some other way. Lucifer is white because Hell thought it would be funny if he fell so hard that it knocked out his melanin (and if he took pride in his appearance, this would double as a punishment— and also give him an interesting parallel to Alastor).
‘Yes, yes, I’m a talking cave…’ (<- deep cut for the real ones)
~ Speaking of literal whitewashing: Lucifer has traits resembling imps (horns, devil tail, yellow sclera / red irises, his short height…), and we can see from Blitzo’s burn marks that imp skin scars white. This is especially interesting, given that A.) his cheeks are red (the color of imp skin), and B.) the way imps are treated parallels the treatment of Mexican-Americans IRL.
~ ... Saint Peter****. Blond-haired, blue-eyed. This, combined with everything else, suggests to me that they're making some commentary on how white features are invisible / go unquestioned, even when their presence SHOULD be unusual.
**** (Sidenote: His little curlicue seems to be a reference to the Sinai encaustic icon. I'm not sure what that adds to the current discussion, but I just thought that was neat.)