Just adding a Diffuse will not give the expected result that you are looking for. You need to also add maps for the Bump/Normal, Specular and Blend - at the least.
One thing that you could try is to add the Leather Material found in the Materials Lib folder to both the head and body and then start making adjustments to see if it works for you.
Gerry
System: Win 10 Pro (21H2), Asus X99-E WS, CPU i7-5930K -3,5 GHz, 32 GB DDR4 2666-16 RAM, NVidia GTX 1080 Ti GPU - 11 GB VRAM(Driver Studio-536.99), Samsung 850 Pro 512 GB SSD, 6 TB HD storage.