She might be feeling a bit jel. Have you other kids, or just the two?
I had a newborn when my eldest was 14 but there were 3 others between the eldest two so she was probably used to new babies arriving!
She was super helpful. And very willing; she was delighted to have a sister after 3 brothers i think and she could look after her sister just as well as i could (apart from the breast feeding!)
She's in her 30s now and still very fond of her little sister (not so little now!)
I don't think YABU because families should be working together to get chores done, and kids do need to take more responsibility as they get older. That is part of growing up.
If she doesn't want to be around the baby just now, she certainly could be helping with some shopping, cooking etc.
Do try to get baby into a good routine - i know all this baby led is the thing just now - but you must still find time for your older DD that's one to one with you. And that's easier if you put baby somewhere else to nap, and get a bedtime routine going in the early months.
Our teens need us more than our babies in many respects so don't treat DD1 as an adult now. She absolutely isn't. She needs your time too.
But - she should chip in and help you out, for sure!