If you use Noelles shield and keep her on the field she can regen party HP. I dont have zhongli, but I dont think he doubles as shielder and Healer..?
If you have Zhongli, you can forgo taking up a healer. His shield is just THAT good, but still you shouldn't be unga-bunga-braindead-ing enemies and taking unnecessary hits, especially from Inazuma mobs.
When it comes to making shields, my mind goes like Zhongli→Noelle→Diona→Ningguang. Even now, when I need a second party that centers not around first choices, Noelle with The Bell is a must.