Is there a frosting similar to whipped cream but without cream?
There are dozens of different types of frosting.

Whipped cream frosting is one of them. It's made very simply by whipping heavy whipping cream until it reaches stiff peaks and then adding a tablespoon or two of sugar to help stabilize it. It is light, airy, and not particularly stable for long periods of time unless it is kept in the refrigerator.

Another very common type of icing is "buttercream" frosting. There are several different kinds of buttercream but the most simple kind is made out of butter whipped together with lots of powdered sugar and a small amount (a tablespoon or two) of liquid - either milk or even various types of alcohol if you want your icing to be boozy. It can be made with most solid fats including margarine or shortening.

Buttercream is pretty stable without being refrigerated but it will not have the same texture (it's more dense and "fatty"). It sounds like you're used to the former but you tried out the latter and you weren't happy with the results - which I understand - it is generally significantly sweeter because you're using cups of sugar instead of a few tablespoons as with whipped cream icing.

If you want to try something that's a bit in between these two products - that has the light, airy texture of whipped cream but is sweeter and doesn't use cream, you might consider trying a "seven-minute icing". It's a cooked, egg-white based icing that is similar to meringue. It's made with egg whites, sugar and cream of tartar (as a stabilizer). Done correctly, it makes lovely fluffy peaks with a shiny gloss.