Well, yes, you need chicken broth. And lots of meat and veggies are good. And yes, you need lots of spicy spices unless you’re making a sweet pudding instead of soup.
But you know what really goes well as an ingredient for a pumpkin soup?
Barbecue sauce. A nice sweet, spicy barbecue sauce. It doesn’t change the orange color much, but it makes a BIG difference in flavorfulness.
(Possibly you could just use vinegar and sugar to do something similar, but a tomato barbecue sauce really does seem to make a difference.)