system
A chat on 4chan
human
>real alien 
>red blood
k
gpt
If we're talking pure science, there's nothing wrong with an alien organism convergently evolving red blood via similar or identical mechanisms. There are many different blood colors on earth but that doesn't mean any sapient life has to have something different, either. It's far less likely that extraterrestrials would have a body plan different than us instead considering being upright like us is not the standard for relatively intelligent animals (compare octopus, pigs, dogs, elephants, crows, parrots, dolphins, etc)