What organ is the first to receive nutrients that have been absorbed from the digestive tract?

That would be the liver.

Liver processes nutrients absorbed into the blood by the small intestine, creating energy-giving glycogen from sugary carbohydrates and converting dietary proteins into new proteins needed for our blood.

If u look at the pic i attached nutrients that have been absorbed by veins surrounding the gastrointestinal tract come together to form the hepatic portal vein and enter the liver. After the changes are made they are taken to the heart by the inferior vena cava and pumped to all of our organs.(by the aorta)