why can red light travel through your finger better then blue light?

Answer 1

Longer wavelenght...able to bend around molecules

Answer 2

The blood in our bodies act as a filter and only lets red light through. Eg. if you look at the sun or a lightsource with your eyes closed you'll see red because our eyelids are thin. Alternitavely you can shine a torch through you hand and it'll look red. The cells absorb all the other wavelengths and reflects/transmits only red light.

Blue light simply does not get through because it gets absorbed. Unlike white light, it lacks the red frequencies that are reflected/transmitted, so no light is seen at all.