Apparently the pale, semi-translucent skin is a mutation that allowed hominids to live at high latitudes, where darker-skinned hominids would whither due to the lack of vitamins of the D group [1].

That same mutation made them vulnerable to the levels of sunlight at lower latitudes, susceptible to sunburns, etc.

[1]: https://pmc.ncbi.nlm.nih.gov/articles/PMC8359960/