I will never know if human blood is actually red as long as it is in the body.
Coulda sworn - now that you mention it - I once read/heard that it’s actually only once blood gets directly exposed to air/oxygen that it ‘turns’ red. (Though I dunno how the oxygenation within the body would differ). In such a case, who knows what Color it’d be within the body.
Or maybe it’s just the observation that ‘colors’ It.
Or maybe that’s all wrong. Haha.