The convention is to name things for their inherent dimensionalitly, not the space they live in.

A sphere in three dimensional space is a two dimensional object, in the sense that it's a surface on which the points can be described by two coordinates (say longitude and latitude).

Similarly a point on a circle can be described by a single coordinate (distance around the circle).

So the 1-sphere is a circle, and normally lives in 2 dimensional space, while the ordinary sphere is called a 2-sphere, and lives in three dimensional space.